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Expired - Lifetime
Application number
US09/376,359
Inventor
David F. Sorrells
Michael J. Bultman
Robert W. Cook
Richard C. Looke
Charley D. Moses, Jr.
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ParkerVision Inc
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ParkerVision Inc
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Application filed by ParkerVision IncfiledCriticalParkerVision Inc
Priority to US09/376,359priorityCriticalpatent/US6266518B1/en
Priority to US09/567,978prioritypatent/US7027786B1/en
Priority to US09/567,977prioritypatent/US7321735B1/en
Application grantedgrantedCritical
Publication of US6266518B1publicationCriticalpatent/US6266518B1/en
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
H04L27/38—Demodulator circuits; Receiver circuits
H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
H04L27/3881—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using sampling and digital processing, not including digital systems which imitate heterodyne or homodyne demodulation
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03C—MODULATION
H03C1/00—Amplitude modulation
H03C1/62—Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
H03D7/14—Balanced arrangements
H03D7/1425—Balanced arrangements with transistors
H03D7/1441—Balanced arrangements with transistors using field-effect transistors
H—ELECTRICITY
H03—ELECTRONIC CIRCUITRY
H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
H03D7/14—Balanced arrangements
H03D7/1425—Balanced arrangements with transistors
H03D7/1475—Subharmonic mixer arrangements
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04B—TRANSMISSION
H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
H04B1/0003—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain
H04B1/0007—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage
H04B1/0025—Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain wherein the AD/DA conversion occurs at radiofrequency or intermediate frequency stage using a sampling rate lower than twice the highest frequency component of the sampled signal
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04B—TRANSMISSION
H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
H04B1/06—Receivers
H04B1/16—Circuits
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04B—TRANSMISSION
H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
H04B1/06—Receivers
H04B1/16—Circuits
H04B1/26—Circuits for superheterodyne receivers
H04B1/28—Circuits for superheterodyne receivers the receiver comprising at least one semiconductor device having three or more electrodes
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04B—TRANSMISSION
H04B7/00—Radio transmission systems, i.e. using radiation field
H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
H04B7/12—Frequency diversity
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L25/00—Baseband systems
H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
H04L25/08—Modifications for reducing interference; Modifications for reducing effects due to line faults ; Receiver end arrangements for detecting or overcoming line faults
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
H04L27/06—Demodulator circuits; Receiver circuits
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
H04L27/14—Demodulator circuits; Receiver circuits
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
H04L27/14—Demodulator circuits; Receiver circuits
H04L27/144—Demodulator circuits; Receiver circuits with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements
H04L27/148—Demodulator circuits; Receiver circuits with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements using filters, including PLL-type filters
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
H04L27/14—Demodulator circuits; Receiver circuits
H04L27/156—Demodulator circuits; Receiver circuits with demodulation using temporal properties of the received signal, e.g. detecting pulse width
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L27/00—Modulated-carrier systems
H04L27/26—Systems using multi-frequency codes
H04L27/2601—Multicarrier modulation systems
H04L27/2647—Arrangements specific to the receiver only
H04L27/2655—Synchronisation arrangements
H04L27/2668—Details of algorithms
H04L27/2669—Details of algorithms characterised by the domain of operation
H04L27/2672—Frequency domain
Definitions
the present inventionrelates to down-conversion of electromagnetic (EM) signals. More particularly, the present invention relates to down-conversion of EM signals to intermediate frequency signals, to direct down-conversion of EM modulated carrier signals to demodulated baseband signals, and to conversion of FM signals to non-FM signals.
the present inventionalso relates to under-sampling and to transferring energy at aliasing rates.
Electromagnetic (EM) information signalsinclude, but are not limited to, video baseband signals, voice baseband signals, computer baseband signals, etc.
Baseband signalsinclude analog baseband signals and digital baseband signals.
Up-conversion to a higher frequencyis utilized.
Conventional up-conversion processesmodulate higher frequency carrier signals with baseband signals. Modulation refers to a variety of techniques for impressing information from the baseband signals onto the higher frequency carrier signals. The resultant signals are referred to herein as modulated carrier signals.
the amplitude of an AM carrier signalvaries in relation to changes in the baseband signal
the frequency of an FM carrier signalvaries in relation to changes in the baseband signal
the phase of a PM carrier signalvaries in relation to changes in the baseband signal.
the informationIn order to process the information that was in the baseband signal, the information must be extracted, or demodulated, from the modulated carrier signal.
conventional signal processing technologyis limited in operational speed, conventional signal processing technology cannot easily demodulate a baseband signal from higher frequency modulated carrier signal directly. Instead, higher frequency modulated carrier signals must be down-converted to an intermediate frequency (IF), from where a conventional demodulator can demodulate the baseband signal.
IFintermediate frequency
Conventional down-convertersinclude electrical components whose properties are frequency dependent. As a result, conventional down-converters are designed around specific frequencies or frequency ranges and do not work well outside their designed frequency range.
Conventional down-convertersgenerate unwanted image signals and thus must include filters for filtering the unwanted image signals.
filtersreduce the power level of the modulated carrier signals.
conventional down-convertersinclude power amplifiers, which require external energy sources.
conventional down-convertersWhen a received modulated carrier signal is relatively weak, as in, for example, a radio receiver, conventional down-converters include additional power amplifiers, which require additional external energy.
the inventionoperates by receiving an EM signal.
the inventionalso receives an aliasing signal having an aliasing rate.
the inventionaliases the EM signal according to the aliasing signal to down-convert the EM signal.
aliasingrefers to both down-converting an EM signal by under-sampling the EM signal at an aliasing rate, and down-converting an EM signal by transferring energy from the EM signal at the aliasing rate.
the inventiondown-converts the EM signal to an intermediate frequency (IF) signal.
IFintermediate frequency
the EM signalis a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal.
FMfrequency modulated
AMamplitude modulated
the inventionis applicable to any type of EM signal, including but not limited to, modulated carrier signals (the invention is applicable to any modulation scheme or combination thereof) and unmodulated carrier signals.
FIG. 1illustrates a structural block diagram of an example modulator
FIG. 2illustrates an example analog modulating baseband signal
FIG. 3illustrates an example digital modulating baseband signal
FIGS. 6A-6Cillustrate example signal diagrams related to amplitude shift keying modulation
FIGS. 8A-8Cillustrate example signal diagrams related to frequency shift keying modulation
FIGS. 9A-9Cillustrate example signal diagrams related to phase modulation
FIGS. 10A-10Cillustrate example signal diagrams related to phase shift keying modulation
FIG. 11illustrates a structural block diagram of a conventional receiver
FIG. 13illustrates a structural block diagram of an aliasing system according to an embodiment of the invention
FIGS. 14A-Dillustrate various flowcharts for down-converting an EM signal by under-sampling the EM signal according to embodiments of the invention
FIGS. 15A-Eillustrate example signal diagrams associated with flowcharts in FIGS. 14A-D according to embodiments of the invention
FIG. 16illustrates a structural block diagram of an under-sampling system according to an embodiment of the invention
FIG. 17illustrates a flowchart of an example process for determining an aliasing rate according to an embodiment of the invention
FIGS. 18A-Eillustrate example signal diagrams associated with down-converting a digital AM signal to an intermediate frequency signal by under-sampling according to embodiments of the invention
FIGS. 19A-Eillustrate example signal diagrams associated with down-converting an analog AM signal to an intermediate frequency signal by under-sampling according to embodiments of the invention
FIGS. 20A-Eillustrate example signal diagrams associated with down-converting an analog FM signal to an intermediate frequency signal by under-sampling according to embodiments of the invention
FIGS. 21A-Eillustrate example signal diagrams associated with down-converting a digital FM signal to an intermediate frequency signal by under-sampling according to embodiments of the invention
FIGS. 22A-Eillustrate example signal diagrams associated with down-converting a digital PM signal to an intermediate frequency signal by under-sampling according to embodiments of the invention
FIGS. 23A-Eillustrate example signal diagrams associated with down-converting an analog PM signal to an intermediate frequency signal by under-sampling according to embodiments of the invention
FIG. 24Aillustrates a structural block diagram of a make before break under-sampling system according to an embodiment of the invention
FIG. 24Billustrates an example timing diagram of an under sampling signal according to an embodiment of the invention
FIG. 24Cillustrates an example timing diagram of an isolation signal according to an embodiment of the invention.
FIGS. 25A-Hillustrate example aliasing signals at various aliasing rates according to embodiments of the invention
FIG. 26Aillustrates a structural block diagram of an exemplary sample and hold system according to an embodiment of the invention
FIG. 26Billustrates a structural block diagram of an exemplary inverted sample and hold system according to an embodiment of the invention
FIG. 27illustrates a structural block diagram of sample and hold module according to an embodiment of the invention
FIGS. 28A-Dillustrate example implementations of a switch module according to embodiments of the invention.
FIGS. 29A-Fillustrate example implementations of a holding module according to embodiments of the present invention.
FIG. 29Gillustrates an integrated under-sampling system according to embodiments of the invention.
FIGS. 29H-Killustrate example implementations of pulse generators according to embodiments of the invention.
FIG. 29Lillustrates an example oscillator
FIG. 30illustrates a structural block diagram of an under-sampling system with an under-sampling signal optimizer according to embodiments of the invention
FIG. 31illustrates a structural block diagram of an under-sampling signal optimizer according to embodiments of the present invention
FIG. 32Aillustrates an example of an under-sampling signal module according to an embodiment of the invention
FIG. 32Billustrates a flowchart of a state machine operation associated with an under-sampling module according to embodiments of the invention
FIG. 32Cillustrates an example under-sampling module that includes an analog circuit with automatic gain control according to embodiments of the invention
FIGS. 33A-Dillustrate example signal diagrams associated with direct down-conversion of an EM signal to a baseband signal by under-sampling according to embodiments of the present invention
FIGS. 34A-Fillustrate example signal diagrams associated with an inverted sample and hold module according to embodiments of the invention
FIGS. 35A-Eillustrate example signal diagrams associated with directly down-converting an analog AM signal to a demodulated baseband signal by under-sampling according to embodiments of the invention
FIGS. 36A-Eillustrate example signal diagrams associated with down-converting a digital AM signal to a demodulated baseband signal by under-sampling according to embodiments of the invention
FIGS. 37A-Eillustrate example signal diagrams associated with directly down-converting an analog PM signal to a demodulated baseband signal by under-sampling according to embodiments of the invention
FIGS. 38A-Eillustrate example signal diagrams associated with down-converting a digital PM signal to a demodulated baseband signal by under-sampling according to embodiments of the invention
FIGS. 39A-Dillustrate down-converting a FM signal to a non-FM signal by under-sampling according to embodiments of the invention
FIGS. 40A-Eillustrate down-converting a FSK signal to a PSK signal by under-sampling according to embodiments of the invention
FIGS. 41A-Eillustrate down-converting a FSK signal to an ASK signal by under-sampling according to embodiments of the invention
FIG. 42illustrates a structural block diagram of an inverted sample and hold module according to an embodiment of the present invention
FIGS. 43A and Billustrate example waveforms present in the circuit of FIG. 31;
FIG. 44Aillustrates a structural block diagram of a differential system according to embodiments of the invention.
FIG. 44Billustrates a structural block diagram of a differential system with a differential input and a differential output according to embodiments of the invention
FIG. 44Cillustrates a structural block diagram of a differential system with a single input and a differential output according to embodiments of the invention
FIG. 44Dillustrates a differential input with a single output according to embodiments of the invention
FIG. 44Eillustrates an example differential input to single output system according to embodiments of the invention.
FIGS. 45A-Billustrate a conceptual illustration of aliasing including under-sampling and energy transfer according to embodiments of the invention
FIGS. 46A-Dillustrate various flowchart for down-converting an EM signal by transferring energy from the EM signal at an aliasing rate according to embodiments of the invention
FIGS. 47A-Eillustrate example signal diagrams associated with the flowcharts in FIGS. 46A-D according to embodiments of the invention
FIG. 48is a flowchart that illustrates an example process for determining an aliasing rate associated with an aliasing signal according to an embodiment of the invention
FIG. 49A-Hillustrate example energy transfer signals according to embodiments of the invention.
FIGS. 50A-Gillustrate example signal diagrams associated with down-converting an analog AM signal to an intermediate frequency by transferring energy at an aliasing rate according to embodiments of the invention
FIGS. 51A-Gillustrate example signal diagrams associated with down-converting an digital AM signal to an intermediate frequency by transferring energy at an aliasing rate according to embodiments of the invention
FIGS. 52A-Gillustrate example signal diagrams associated with down-converting an analog FM signal to an intermediate frequency by transferring energy at an aliasing rate according to embodiments of the invention
FIGS. 53A-Gillustrate example signal diagrams associated with down-converting an digital FM signal to an intermediate frequency by transferring energy at an aliasing rate according to embodiments of the invention
FIGS. 54A-Gillustrate example signal diagrams associated with down-converting an analog PM signal to an intermediate frequency by transferring energy at an aliasing rate according to embodiments of the invention
FIGS. 55A-Gillustrate example signal diagrams associated with down-converting an digital PM signal to an intermediate frequency by transferring energy at an aliasing rate according to embodiments of the invention
FIGS. 56A-Dillustrate an example signal diagram associated with direct down-conversion according to embodiments of the invention
FIGS. 57A-Fillustrate directly down-converting an analog AM signal to a demodulated baseband signal according to embodiments of the invention
FIGS. 58A-Fillustrate directly down-converting an digital AM signal to a demodulated baseband signal according to embodiments of the invention
FIGS. 59A-Fillustrate directly down-converting an analog PM signal to a demodulated baseband signal according to embodiments of the invention
FIGS. 60A-Fillustrate directly down-converting an digital PM signal to a demodulated baseband signal according to embodiments of the invention
FIGS. 61A-Fillustrate down-converting an FM signal to a PM signal according to embodiments of the invention
FIGS. 62A-Fillustrate down-converting an FM signal to a AM signal according to embodiments of the invention
FIG. 63illustrates a block diagram of an energy transfer system according to an embodiment of the invention.
FIG. 64Aillustrates an exemplary gated transfer system according to an embodiment of the invention
FIG. 64Billustrates an exemplary inverted gated transfer system according to an embodiment of the invention
FIG. 65illustrates an example embodiment of the gated transfer module according to an embodiment of the invention.
FIGS. 66A-Dillustrate example implementations of a switch module according to embodiments of the invention.
FIG. 67Aillustrates an example embodiment of the gated transfer module as including a break-before-make module according to an embodiment of the invention
FIG. 67Billustrates an example timing diagram for an energy transfer signal according to an embodiment of the invention
FIG. 67Cillustrates an example timing diagram for an isolation signal according to an embodiment of the invention.
FIGS. 68A-Fillustrate example storage modules according to embodiments of the invention.
FIG. 68Gillustrates an integrated gated transfer system according to an embodiment of the invention
FIGS. 68H-Killustrate example aperature generators
FIG. 68Lillustrates an oscillator according to an embodiment of the present invention
FIG. 69illustrates an energy transfer system with an optional energy transfer signal module according to an embodiment of the invention
FIG. 70illustrates an aliasing module with input and output impedance match according to an embodiment of the invention
FIG. 71illustrates an example pulse generator
FIGS. 72A and Billustrate example waveforms related to the pulse generator of FIG. 71;
FIG. 73illustrates an example energy transfer module with a switch module and a reactive storage module according to an embodiment of the invention
FIG. 74illustrates an example inverted gated transfer module as including a switch module and a storage module according to an embodiment of the invention
FIGS. 75A-Fillustrate an example signal diagrams associated with an inverted gated energy transfer module according to embodiments of the invention.
FIGS. 76A-Eillustrate energy transfer modules in configured in various differential configurations according to embodiments of the invention.
FIGS. 77A-Cillustrate example impedance matching circuits according to embodiments of the invention.
FIGS. 78A-Billustrate example under-sampling systems according to embodiments of the invention.
FIGS. 79A-Fillustrate example timing diagrams for under-sampling systems according to embodiments of the invention.
FIGS. 80A-Fillustrate example timing diagrams for an under-sampling system when the load is a relatively low impedance load according to embodiments of the invention
FIGS. 81A-Fillustrate example timing diagrams for an under-sampling system when the holding capacitance has a larger value according to embodiments of the invention
FIGS. 82A-Billustrate example energy transfer systems according to embodiments of the invention.
FIGS. 83A-Fillustrate example timing diagrams for energy transfer systems according to embodiments of the present invention.
FIGS. 84A-Dillustrate down-converting an FSK signal to a PSK signal according to embodiments of the present invention
FIG. 85Aillustrates an example energy transfer signal module according to an embodiment of the present invention
FIG. 85Billustrates a flowchart of state machine operation according to an embodiment of the present invention.
FIG. 85Cis an example energy transfer signal module
FIG. 86is a schematic diagram of a circuit to down-convert a 915 MHZ signal to a 5 MHZ signal using a 101.1 MHZ clock according to an embodiment of the present invention
FIG. 87shows simulation waveforms for the circuit of FIG. 86 according to embodiments of the present invention.
FIG. 88is a schematic diagram of a circuit to down-convert a 915 MHZ signal to a 5 MHz signal using a 101 MHZ clock according to an embodiment of the present invention
FIG. 89shows simulation waveforms for the circuit of FIG. 88 according to embodiments of the present invention.
FIG. 90is a schematic diagram of a circuit to down-convert a 915 MHZ signal to a 5 MHZ signal using a 101.1 MHZ clock according to an embodiment of the present invention
FIG. 91shows simulation waveforms for the circuit of FIG. 90 according to an embodiment it of the present invention.
FIG. 92shows a schematic of the circuit in FIG. 86 connected to an FSK source that alternates between 913 and 917 MHZ at a baud rate of 500 Kbaud according to an embodiment of the present invention
FIG. 93shows the original FSK waveform 9202 and the down-converted waveform 9204 at the output of the load impedance match circuit according to an embodiment of the present invention
FIG. 94Aillustrates an example energy transfer system according to an embodiment of the invention
FIGS. 94B-Cillustrate example timing diagrams for the example system of FIG. 94A
FIG. 95illustrates an example bypass network according to an embodiment of the invention.
FIGS. 96 and 97illustrate the amplitude and pulse width modulated transmitter according to embodiments of the present invention
FIGS. 98A-D, 99 , 100illustrate example signal diagrams associated with the amplitude and pulse width modulated transmitter according to embodiments of the present invention
FIG. 101shows an embodiment of a receiver block diagram to recover the amplitude or pulse width modulated information
FIGS. 102A-Fillustrates example signal diagrams associated with a waveform generator according to embodiments of the present invention
FIGS. 103-105are example schematic diagrams illustrating various circuits employed in the receiver of FIG. A 6 ;
FIGS. 106-109illustrate time and frequency domain diagrams of alternative transmitter output waveforms
FIGS. 110-111illustrate differential receivers in accord with embodiments of the present invention.
FIGS. 112 and 113illustrate time and frequency domains for a narrow bandwidth/constant carrier signal in accord with an embodiment of the present invention.
flowchartssuch as flowchart 1201 in FIG. 12 A.
flowchart 1201the operation of the invention is often represented by flowcharts, such as flowchart 1201 in FIG. 12 A.
flowchartsthe use of flowcharts is for illustrative purposes only, and is not limiting.
the inventionis not limited to the operational embodiment(s) represented by the flowcharts. Instead, alternative operational embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion contained herein.
the use of flowchartsshould not be interpreted as limiting the invention to discrete or digital operation. In practice, as will be appreciated by persons skilled in the relevant art(s) based on the herein discussion, the invention can be achieved via discrete or continuous operation, or a combination thereof.
modulated carrier signalwhen used herein, refers to a carrier signal that is modulated by a baseband signal.
unmodulated carrier signalwhen used herein, refers to a signal having an amplitude that oscillates at a substantially uniform frequency and phase.
baseband signalwhen used herein, refers to an information signal including, but not limited to, analog information signals, digital information signals and direct current (DC) information signals.
carrier signalwhen used herein, and unless otherwise specified when used herein, refers to modulated carrier signals and unmodulated carrier signals.
electromagnetic (EM) signalwhen used herein, refers to a signal in the EM spectrum.
EM spectrumincludes all frequencies greater than zero hertz.
EM signalsgenerally include waves characterized by variations in electric and magnetic fields. Such waves may be propagated in any medium, both natural and manmade, including but not limited to air, space, wire, cable, liquid, waveguide, micro-strip, strip-line, optical fiber, etc. Unless stated otherwise, all signals discussed herein are EM signals, even when not explicitly designated as such.
intermediate frequency (IF) signalwhen used herein, refers to an EM signal that is substantially similar to another EM signal except that the IF signal has a lower frequency than the other signal.
An IF signal frequencycan be any frequency above zero HZ. Unless otherwise stated, the terms lower frequency, intermediate frequency, intermediate and IF are used interchangeably herein.
analog signalwhen used herein, refers to a signal that is constant or continuously variable, as contrasted to a signal that changes between discrete states.
basebandwhen used herein, refers to a frequency band occupied by any generic information signal desired for transmission and/or reception.
baseband signalwhen used herein, refers to any generic information signal desired for transmission and/or reception.
carrier frequencywhen used herein, refers to the frequency of a carrier signal. Typically, it is the center frequency of a transmission signal that is generally modulated.
carrier signalwhen used herein, refers to an EM wave having at least one characteristic that may be varied by modulation, that is capable of carrying information via modulation.
demodulated baseband signalwhen used herein, refers to a signal that results from processing a modulated signal.
the demodulated baseband signalresults from demodulating an intermediate frequency (IF) modulated signal, which results from down converting a modulated carrier signal.
IFintermediate frequency
a signal that results from a combined downconversion and demodulation stepa signal that results from a combined downconversion and demodulation step.
digital signalwhen used herein, refers to a signal that changes between discrete states, as contrasted to a signal that is continuous. For example, the voltage of a digital signal may shift between discrete levels.
electromagnetic (EM) spectrumwhen used herein, refers to a spectrum comprising waves characterized by variations in electric and magnetic fields. Such waves may be propagated in any communication medium, both natural and manmade, including but not limited to air, space, wire, cable, liquid, waveguide, microstrip, stripline, optical fiber, etc.
the EM spectrumincludes all frequencies greater than zero hertz.
electromagnetic (EM) signalwhen used herein, refers to a signal in the EM spectrum. Also generally called an EM wave. Unless stated otherwise, all signals discussed herein are EM signals, even when not explicitly designated as such.
modulating baseband signalwhen used herein, refers to any generic information signal that is used to modulate an oscillating signal, or carrier signal.
EMelectromagnetic
baseband signalssuch as digital data information signals and analog information signals.
a baseband signalcan be up-converted to a higher frequency EM signal by using the baseband signal to modulate a higher frequency carrier signal, F C .
F Mmodulating baseband signal
Modulationimparts changes to the carrier signal F C that represent information in the modulating baseband signal F MB .
the changescan be in the form of amplitude changes, frequency changes, phase changes, etc., or any combination thereof.
the resultant signalis referred to herein as a modulated carrier signal F MC .
the modulated carrier signal F MCincludes the carrier signal F C modulated by the modulating baseband signal, F MB , as in:
the modulated carrier signal F MCoscillates at, or near the frequency of the carrier signal F C and can thus be efficiently propagated.
FIG. 1illustrates an example modulator 110 , wherein the carrier signal F C is modulated by the modulating baseband signal F MB , thereby generating the modulated carrier signal F MC .
Modulating baseband signal F MBcan be an analog baseband signal, a digital baseband signal, or a combination thereof.
FIG. 2illustrates the modulating baseband signal F MB as an exemplary analog modulating baseband signal 210 .
the exemplary analog modulating baseband signal 210can represent any type of analog information including, but not limited to, voice/speech data, music data, video data, etc.
the amplitude of analog modulating baseband signal 210varies in time.
Digital informationincludes a plurality of discrete states. For ease of explanation, digital information signals are discussed below as having two discrete states. But the invention is not limited to this embodiment.
FIG. 3illustrates the modulating baseband signal F MB as an exemplary digital modulating baseband signal 310 .
the digital modulating baseband signal 310can represent any type of digital data including, but not limited to, digital computer information and digitized analog information.
the digital modulating baseband signal 310includes a first state 312 and a second state 314 .
first state 312represents binary state 0 and second state 314 represents binary state 1.
first state 312represents binary state 1 and second state 314 represents binary state 0.
the former conventionis followed, whereby first state 312 represents binary state zero and second state 314 represents binary state one. But the invention is not limited to this embodiment.
First state 312is thus referred to herein as a low state and second state 314 is referred to herein as a high state.
Digital modulating baseband signal 310can change between first state 312 and second state 314 at a data rate, or baud rate, measured as bits per second.
Carrier signal F Cis modulated by the modulating baseband signal F MB , by any modulation technique, including, but not limited to, amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), etc., or any combination thereof. Examples are provided below for amplitude modulating, frequency modulating, and phase modulating the analog modulating baseband signal 210 and the digital modulating baseband signal 310 , on the carrier signal F C . The examples are used to assist in the description of the invention. The invention is not limited to, or by, the examples.
FIG. 4illustrates the carrier signal F C as a carrier signal 410 .
the carrier signal 410is illustrated as a 900 MHZ carrier signal.
the carrier signal 410can be any other frequency.
Example modulation schemesare provided below, using the examples signals from FIGS. 2, 3 and 4 .
FIGS. 5A-5Cillustrate example timing diagrams for amplitude modulating the carrier signal 410 with the analog modulating baseband signal 210 .
FIGS. 6A-6Cillustrate example timing diagrams for amplitude modulating the carrier signal 410 with the digital modulating baseband signal 310 .
FIG. 5Aillustrates the analog modulating baseband signal 210 .
FIG. 5Billustrates the carrier signal 410 .
FIG. 5Cillustrates an analog AM carrier signal 516 , which is generated when the carrier signal 410 is amplitude modulated using the analog modulating baseband signal 210 .
analog AM carrier signalis used to indicate that the modulating baseband signal is an analog signal.
the analog AM carrier signal 516oscillates at the frequency of carrier signal 410 .
the amplitude of the analog AM carrier signal 516tracks the amplitude of analog modulating baseband signal 210 , illustrating that the information contained in the analog modulating baseband signal 210 is retained in the analog AM carrier signal 516 .
FIG. 6Aillustrates the digital modulating baseband signal 310 .
FIG. 6Billustrates the carrier signal 410 .
FIG. 6Cillustrates a digital AM carrier signal 616 , which is generated when the carrier signal 410 is amplitude modulated using the digital modulating baseband signal 310 .
digital AM carrier signalis used to indicate that the modulating baseband signal is a digital signal.
the digital AM carrier signal 616oscillates at the frequency of carrier signal 410 .
the amplitude of the digital AM carrier signal 616tracks the amplitude of digital modulating baseband signal 310 , illustrating that the information contained in the digital modulating baseband signal 310 is retained in the digital AM signal 616 .
the digital AM signal 616shifts amplitudes.
Digital amplitude modulationis often referred to as amplitude shift keying (ASK), and the two terms are used interchangeably throughout the specification.
FIGS. 7A-7Cillustrate example timing diagrams for frequency modulating the carrier signal 410 with the analog modulating baseband signal 210 .
FIGS. 8A-8Cillustrate example timing diagrams for frequency modulating the carrier signal 410 with the digital modulating baseband signal 310 .
FIG. 7Aillustrates the analog modulating baseband signal 210 .
FIG. 7Billustrates the carrier signal 410 .
FIG. 7Cillustrates an analog FM carrier signal 716 , which is generated when the carrier signal 410 is frequency modulated using the analog modulating baseband signal 210 .
analog FM carrier signalis used to indicate that the modulating baseband signal is an analog signal.
the frequency of the analog FM carrier signal 716varies as a function of amplitude changes on the analog baseband signal 210 .
the frequency of the analog FM carrier signal 716varies in proportion to the amplitude of the analog modulating baseband signal 210 .
the amplitude of the analog baseband signal 210 and the frequency of the analog FM carrier signal 716are at maximums.
the amplitude of the analog baseband signal 210 and the frequency of the analog FM carrier signal 716are at minimums.
the frequency of the analog FM carrier signal 716is typically centered around the frequency of the carrier signal 410 .
the frequency of the analog FM carrier signal 716is substantially the same as the frequency of the carrier signal 410 .
FIG. 8Aillustrates the digital modulating baseband signal 310 .
FIG. 8Billustrates the carrier signal 410 .
FIG. 8Cillustrates a digital FM carrier signal 816 , which is generated when the carrier signal 410 is frequency modulated using the digital baseband signal 310 .
digital FM carrier signalis used to indicate that the modulating baseband signal is a digital signal.
the frequency of the digital FM carrier signal 816varies as a function of amplitude changes on the digital modulating baseband signal 310 .
the frequency of the digital FM carrier signal 816varies in proportion to the amplitude of the digital modulating baseband signal 310 .
the frequency of the digital FM carrier signal 816is at a maximum.
the frequency of the digital FM carrier signal 816is at a minimum.
Digital frequency modulationis often referred to as frequency shift keying (FSK), and the terms are used interchangeably throughout the specification.
the frequency of the digital FM carrier signal 816is centered about the frequency of the carrier signal 410 , and the maximum and minimum frequencies are equally offset from the center frequency.
the frequency of the digital FM carrier signal 816is centered about the frequency of the carrier signal 410 , and the maximum and minimum frequencies are equally offset from the center frequency.
this conventionwill be followed herein.
phase modulationIn phase modulation (PM), the phase of the modulated carrier signal F MC varies as a function of the amplitude of the modulating baseband signal F MB .
FIGS. 9A-9Cillustrate example timing diagrams for phase modulating the carrier signal 410 with the analog modulating baseband signal 210 .
FIGS. 10A-10Cillustrate example timing diagrams for phase modulating the carrier signal 410 with the digital modulating baseband signal 310 .
FIG. 9Aillustrates the analog modulating baseband signal 210 .
FIG. 9Billustrates the carrier signal 410 .
FIG. 9Cillustrates an analog PM carrier signal 916 , which is generated by phase modulating the carrier signal 410 with the analog baseband signal 210 .
analog PM carrier signalis used to indicate that the modulating baseband signal is an analog signal.
the frequency of the analog PM carrier signal 916is substantially the same as the frequency of carrier signal 410 .
the phase of the analog PM carrier signal 916varies with amplitude changes on the analog modulating baseband signal 210 .
the carrier signal 410is illustrated in FIG. 9C by a dashed line.
the phase of the analog PM carrier signal 916varies as a function of amplitude changes of the analog baseband signal 210 .
the phase of the analog PM signal 916lags by a varying amount as determined by the amplitude of the baseband signal 210 .
the analog PM carrier signal 916is in phase with the carrier signal 410 .
the phase of the analog PM carrier signal 916lags the phase of the carrier signal 410 , until it reaches a maximum out of phase value at time t3.
the phase changeis illustrated as approximately 180 degrees. Any suitable amount of phase change, varied in any manner that is a function of the baseband signal, can be utilized.
FIG. 10Aillustrates the digital modulating baseband signal 310 .
FIG. 10Billustrates the carrier signal 410 .
FIG. 10Cillustrates a digital PM carrier signal 1016 , which is generated by phase modulating the carrier signal 410 with the digital baseband signal 310 .
digital PM carrier signalis used to indicate that the modulating baseband signal is a digital signal.
the frequency of the digital PM carrier signal 1016is substantially the same as the frequency of carrier signal 410 .
the phase of the digital PM carrier signal 1016varies as a function of amplitude changes on the digital baseband signal 310 .
the digital baseband signal 310is at the first state 312
the digital PM carrier signal 1016is out of phase with the carrier signal 410 .
the digital baseband signal 310is at the second state 314
the digital PM carrier signal 1016is in-phase with the carrier signal 410 .
the digital PM carrier signal 1016is out of phase with the carrier signal 410 between times to and t1, and between times t2 and t4, when the amplitude of the digital baseband signal 310 is at the second state 314 , the digital PM carrier signal 1016 is in phase with the carrier signal 410 .
phase shift keyingPSK
the modulated carrier signal F MCWhen the modulated carrier signal F MC is received, it can be demodulated to extract the modulating baseband signal F MB . Because of the typically high frequency of modulated carrier signal F MC , however, it is generally impractical to demodulate the baseband signal F MB directly from the modulated carrier signal F MC . Instead, the modulated carrier signal F MC must be down-converted to a lower frequency signal that contains the original modulating baseband signal.
the lower frequency signalWhen a modulated carrier signal is down-converted to a lower frequency signal, the lower frequency signal is referred to herein as an intermediate frequency (IF) signal F IF .
the IF signal F IFoscillates at any frequency, or frequency band, below the frequency of the modulated carrier frequency F MC . Down-conversion of F MC to F IF is illustrated as:
F IFcan be demodulated to a baseband signal F DMB , as illustrated by:
F DMBis intended to be substantially similar to the modulating baseband signal F MB , illustrating that the modulating baseband signal F MB can be substantially recovered.
a carrier signalcan be modulated with a plurality of the modulation types described above.
a carrier signalcan also be modulated with a plurality of baseband signals, including analog baseband signals, digital baseband signals, and combinations of both analog and digital baseband signals.
the present inventionis a method and system for down-converting an electromagnetic (EM) signal by aliasing the EM signal. Aliasing is represented generally in FIG. 45A as 4502 .
the inventioncan down-convert that carrier to lower frequencies.
One aspect that can be exploited by this inventionis realizing that the carrier is not the item of interest, the lower baseband signal is of interest to reproduce sufficiently. This baseband signal's frequency content, even though its carrier may be aliased, does satisfy the Nyquist criteria and as a result, the baseband information can be sufficiently reproduced.
FIG. 12Adepicts a flowchart 1201 that illustrates a method for aliasing an EM signal to generate a down-converted signal.
the processbegins at step 1202 , which includes receiving the EM signal.
Step 1204includes receiving an aliasing signal having an aliasing rate.
Step 1206includes aliasing the EM signal to down-convert the EM signal.
aliasingrefers to both down-converting an EM signal by under-sampling the EM signal at an aliasing rate and to down-converting an EM signal by transferring energy from the EM signal at the aliasing rate.
FIG. 13illustrates a block diagram of a generic aliasing system 1302 , which includes an aliasing module 1306 .
the aliasing system 1302operates in accordance with the flowchart 1201 .
the aliasing module 1306receives an EM signal 1304 .
the aliasing module 1306receives an aliasing signal 1310 .
the aliasing module 1306down-converts the EM signal 1304 to a down-converted signal 1308 .
the generic aliasing system 1302can also be used to implement any of the flowcharts 1207 , 1213 and 1219 .
the inventiondown-converts the EM signal to an intermediate frequency (IF) signal.
FIG. 12Bdepicts a flowchart 1207 that illustrates a method for under-sampling the EM signal at an aliasing rate to down-convert the EM signal to an IF signal.
the processbegins at step 1208 , which includes receiving an EM signal.
Step 1210includes receiving an aliasing signal having an aliasing rate F AR .
Step 1212includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to an IF signal.
the inventiondown-converts the EM signal to a demodulated baseband information signal.
FIG. 12Cdepicts a flowchart 1213 that illustrates a method for down-converting the EM signal to a demodulated baseband signal.
the processbegins at step 1214 , which includes receiving an EM signal.
Step 1216includes receiving an aliasing signal having an aliasing rate F AR .
Step 1218includes down-converting the EM signal to a demodulated baseband signal.
the demodulated baseband signalcan be processed without further down-conversion or demodulation.
the EM signalis a frequency modulated (FM) signal, which is down-converted to a non-FM signal, such as a phase modulated (PM) signal or an amplitude modulated (AM) signal.
FIG. 12Ddepicts a flowchart 1219 that illustrates a method for down-converting the FM signal to a non-FM signal. The process begins at step 1220 , which includes receiving an EM signal. Step 1222 includes receiving an aliasing signal having an aliasing rate. Step 1224 includes down-converting the FM signal to a non-FM signal.
the inventiondown-converts any type of EM signal, including, but not limited to, modulated carrier signals and unmodulated carrier signals.
modulated carrier signalsFor ease of discussion, the invention is further described herein using modulated carrier signals for examples.
the inventioncan be implemented to down-convert signals other than carrier signals as well. The invention is not limited to the example embodiments described above.
down-conversionis accomplished by under-sampling an EM signal. This is described generally in Section I2.2. below and in detail in Section II and its sub-sections. In another embodiment, down-conversion is achieved by transferring non-negligible amounts of energy from an EM signal. This is described generally in Section I.2.3. below and in detail in Section III.
FIG. 14Adepicts a flowchart 1401 that illustrates a method for under-sampling the EM signal at an aliasing rate to down-convert the EM signal.
the processbegins at step 1402 , which includes receiving an EM signal.
Step 1404includes receiving an under-sampling signal having an aliasing rate.
Step 1406includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal.
an EM signalis under-sampled at an aliasing rate to down-convert the EM signal to a lower, or intermediate frequency (IF) signal.
the EM signalcan be a modulated carrier signal or an unmodulated carrier signal.
a modulated carrier signal F MCis down-converted to an IF signal F IF .
FIG. 14Bdepicts a flowchart 1407 that illustrates a method for under-sampling the EM signal at an aliasing rate to down-convert the EM signal to an IF signal.
the processbegins at step 1408 , which includes receiving an EM signal.
Step 1410includes receiving an under-sampling signal having an aliasing rate.
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to an IF signal.
This embodimentis illustrated generally by 4508 in FIG. 45 B and is described in Section II.1.
an EM signalis directly down-converted to a demodulated baseband signal (direct-to-data down-conversion), by under-sampling the EM signal at an aliasing rate.
the EM signalcan be a modulated EM signal or an unmodulated EM signal.
the EM signalis the modulated carrier signal F MC , and is directly down-converted to a demodulated baseband signal F DMB .
FIG. 14Cdepicts a flowchart 1413 that illustrates a method for under-sampling the EM signal at an aliasing rate to directly down-convert the EM signal to a demodulated baseband signal.
the processbegins at step 1414 , which includes receiving an EM signal.
Step 1416includes receiving an under-sampling signal having an aliasing rate.
Step 1418includes under-sampling the EM signal at the aliasing rate to directly down-convert the EM signal to a baseband information signal.
This embodimentis illustrated generally by 4510 in FIG. 45 B and is described in Section II.2
a frequency modulated (FM) carrier signal F FMCis converted to a non-FM signal F (NON-FM) , by under-sampling the FM carrier signal F FMC .
FIG. 14Ddepicts a flowchart 1419 that illustrates a method for under-sampling an FM signal to convert it to a non-FM signal.
the processbegins at step 1420 , which includes receiving the FM signal.
Step 1422includes receiving an under-sampling signal having an aliasing rate.
Step 1424includes under-sampling the FM signal at the aliasing rate to convert the FM signal to a non-FM signal.
the FM signalcan be under-sampled to convert it to a PM signal or an AM signal.
This embodimentis illustrated generally by 4512 in FIG. 45B, and described in Section II.3
aliasingrefers both to down-converting an EM signal by under-sampling the EM signal at an aliasing rate and to down-converting an EM signal by transferring non-negligible amounts energy from the EM signal at the aliasing rate.
FIG. 46Adepicts a flowchart 4601 that illustrates a method for transferring energy from the EM signal at an aliasing rate to down-convert the EM signal.
the processbegins at step 4602 , which includes receiving an EM signal.
Step 4604includes receiving an energy transfer signal having an aliasing rate.
Step 4606includes transferring energy from the EM signal at the aliasing rate to down-convert the EM signal.
Down-converting by transferring energyis illustrated by 4506 in FIG. 45 A and is described in greater detail in Section III.
EM signalis down-converted to a lower, or intermediate frequency (IF) signal, by transferring energy from the EM signal at an aliasing rate.
the EM signalcan be a modulated carrier signal or an unmodulated carrier signal.
a modulated carrier signal F MCis down-converted to an IF signal F IF .
FIG. 46Bdepicts a flowchart 4607 that illustrates a method for transferring energy from the EM signal at an aliasing rate to down-convert the EM signal to an IF signal.
the processbegins at step 4608 , which includes receiving an EM signal.
Step 4610includes receiving an energy transfer signal having an aliasing rate.
Step 4612includes transferring energy from the EM signal at the aliasing rate to down-convert the EM signal to an IF signal.
This embodimentis illustrated generally by 4514 in FIG. 45 B and is described in Section III.1.
an EM signalis down-converted to a demodulated baseband signal by transferring energy from the EM signal at an aliasing rate.
This embodimentis referred to herein as direct-to-data down-conversion.
the EM signalcan be a modulated EM signal or an unmodulated EM signal.
the EM signalis the modulated carrier signal F MC , and is directly down-converted to a demodulated baseband signal F DMB .
FIG. 46Cdepicts a flowchart 4613 that illustrates a method for transferring energy from the EM signal at an aliasing rate to directly down-convert the EM signal to a demodulated baseband signal.
the processbegins at step 4614 , which includes receiving an EM signal.
Step 4616includes receiving an energy transfer signal having an aliasing rate.
Step 4618includes transferring energy from the EM signal at the aliasing rate to directly down-convert the EM signal to a baseband signal.
This embodimentis illustrated generally by 4516 in FIG. 45 B and is described in Section III.2
a frequency modulated (FM) carrier signal F FMCis converted to a non-FM signal F (NON-FM) ,by transferring energy from the FM carrier signal F FMC at an aliasing rate.
FMfrequency modulated
the FM carrier signal F FMCcan be converted to, for example, a phase modulated (PM) signal or an amplitude modulated (AM) signal.
FIG. 46Ddepicts a flowchart 4619 that illustrates a method for transferring energy from an FM signal to convert it to a non-FM signal.
Step 4620includes receiving the FM signal.
Step 4622includes receiving an energy transfer signal having an aliasing rate.
step 4612includes transferring energy from the FM signal to convert it to a non-FM signal. For example, energy can be transferred from an FSK signal to convert it to a PSK signal or an ASK signal.
This embodimentis illustrated generally by 4518 in FIG. 45B, and described in Section III.3
the aliasing rateis equal to, or less than, twice the frequency of the EM carrier signal.
the aliasing rateis much less than the frequency of the carrier signal.
the aliasing rateis preferably more than twice the highest frequency component of the modulating baseband signal F MB that is to be reproduced. The above requirements are illustrated in EQ. (1).
the inventioncan down-convert that carrier to lower frequencies.
the carrieris not the item of interest; instead the lower baseband signal is of interest to be reproduced sufficiently.
the baseband signal's frequency contenteven though its carrier may be aliased, satisfies the Nyquist criteria and as a result, the baseband information can be sufficiently reproduced, either as the intermediate modulating carrier signal F IF or as the demodulated direct-to-data baseband signal F DMB .
F Cis the frequency of the EM carrier signal that is to be aliased
F ARis the aliasing rate
F IFis the intermediate frequency of the down-converted signal.
FIG. 11illustrates an example conventional receiver system 1102 .
the conventional system 1102is provided both to help the reader to understand the functional differences between conventional systems and the present invention, and to help the reader to understand the benefits of the present invention.
the example conventional receiver system 1102receives an electromagnetic (EM) signal 1104 via an antenna 1106 .
the EM signal 1104can include a plurality of EM signals such as modulated carrier signals.
the EM signal 1104includes one or more radio frequency (RF) EM signals, such as a 900 MHZ modulated carrier signal.
RFradio frequency
Higher frequency RF signals, such as 900 MHZ signalsgenerally cannot be directly processed by conventional signal processors. Instead, higher frequency RF signals are typically down-converted to lower intermediate frequencies (IF) for processing.
the receiver system 1102down-converts the EM signal 1104 to an intermediate frequency (IF) signal 1108 n , which can be provided to a signal processor 1110 .
the signal processor 1110usually includes a demodulator that demodulates the IF signal 1108 n to a baseband information signal (demodulated baseband signal).
Receiver system 1102includes an RF stage 1112 and one or more IF stages 1114 .
the RF stage 1112receives the EM signal 1104 .
the RF stage 1112includes the antenna 1106 that receives the EM signal 1104 .
the one or more IF stages 1114 a - 1114 ndown-convert the EM signal 1104 to consecutively lower intermediate frequencies.
Each of the one or more IF sections 1114 a - 1114 nincludes a mixer 1118 a - 1118 n that down-converts an input EM signal 1116 to a lower frequency IF signal 1108 .
the EM signal 1104is incrementally down-converted to a desired IF signal 1108 n.
each of the one or more mixers 1118mixes an input EM signal 1116 with a local oscillator (LO) signal 1119 , which is generated by a local oscillator (LO) 1120 .
Mixinggenerates sum and difference signals from the input EM signal 1116 and the LO signal 1119 .
LOlocal oscillator
mixing an input EM signal 1116 ahaving a frequency of 900 MHZ
a LO signal 1119 ahaving a frequency of 830 MHZ
the one or more mixers 1118generate a sum and difference signals for all signal components in the input EM signal 1116 .
mixing two input EM signals, having frequencies of 900 MHZ and 760 MHZ, respectively, with an LO signal having a frequency of 830 MHZresults in two IF signals at 70 MHZ.
one or more filters 1122 and 1123are provided upstream from each mixer 1118 to filter the unwanted frequencies, also known as image frequencies.
the filters 1122 and 1123can include various filter topologies and arrangements such as bandpass filters, one or more high pass filters, one or more low pass filters, combinations thereof, etc.
the one or more mixers 1118 and the one or more filters 1122 and 1123attenuate or reduce the strength of the EM signal 1104 .
a typical mixerreduces the EM signal strength by 8 to 12 dB.
a typical filterreduces the EM signal strength by 3 to 6 dB.
one or more low noise amplifiers (LNAs) 1121 and 1124 a - 1124 nare provided upstream of the one or more filters 1123 and 1122 a - 1122 n .
the LNAs and filterscan be in reversed order.
the LNAscompensate for losses in the mixers 1118 , the filters 1122 and 1123 , and other components by increasing the EM signal strength prior to filtering and mixing.
each LNAcontributes 15 to 20 dB of amplification.
LNAsrequire substantial power to operate. Higher frequency LNAs require more power than lower frequency LNAs.
the INAsrequire a substantial portion of the total power.
each componentshould be impedance matched with adjacent components. Since no two components have the exact same impedance characteristics, even for components that were manufactured with high tolerances, impedance matching must often be individually fine tuned for each receiver system 1102 . As a result, impedance matching in conventional receivers tends to be labor intensive and more art than science. Impedance matching requires a significant amount of added time and expense to both the design and manufacture of conventional receivers. Since many of the components, such as LNA, filters, and impedance matching circuits, are highly frequency dependent, a receiver designed for one application is generally not suitable for other applications. Instead, a new receiver must be designed, which requires new impedance matching circuits between many of the components.
the present inventionis implemented to replace many, if not all, of the components between the antenna 1106 and the signal processor 1110 , with an aliasing module that includes a universal frequency translator (UIT) module.
UFTuniversal frequency translator
the UFTis able to down-convert a wide range of EM signal frequencies using very few components.
the UFTis easy to design and build, and requires very little external power.
the UFr designcan be easily tailored for different frequencies or frequency ranges. For example, UFF design can be easily impedance matched with relatively little tuning.
the inventionalso eliminates the need for a demodulator in the signal processor 1110 .
the inventioncan be implemented and tailored for specific applications with easy to calculate and easy to implement impedance matching circuits.
the inventionwhen the invention is implemented as a receiver, such as the receiver 1102 , specialized impedance matching experience is not required.
components in the IF sectionscomprise roughly eighty to ninety percent of the total components of the receivers.
the UFI designeliminates the IF section(s) and thus eliminates the roughly eighty to ninety percent of the total components of conventional receivers.
the inventioncan be implemented as a receiver with only a single local oscillator
the inventioncan be implemented as a receiver with only a single, lower frequency, local oscillator
the inventioncan be implemented as a receiver using few filters
the inventioncan be implemented as a receiver using unit delay filters
the inventioncan be implemented as a receiver that can change frequencies and receive different modulation formats with no hardware changes;
the inventioncan be also be implemented as frequency up-converter in an EM signal transmitter
the inventioncan be also be implemented as a combination up-converter (transmitter) and down-converter (receiver), referred to herein as a transceiver;
the inventioncan be implemented as a method and system for ensuring reception of a communications signal, as disclosed in co-pending patent application titled, “Method and System for Ensuring Reception of a Communications Signal,” Attorney Docket No. 1744.0030000, incorporated herein by reference in its entirety;
the inventioncan be implemented in a differential configuration, whereby signal to noise ratios are increased;
a receiver designed in accordance with the inventioncan be implemented on a single IC substrate, such as a silicon-based IC substrate;
a receiver designed in accordance with the invention and implemented on a single IC substrate, such as a silicon-based IC substrate,can down-convert EM signals from frequencies in the giga Hertz range;
a receiver built in accordance with the inventionhas a relatively flat response over a wide range of frequencies.
a receiver built in accordance with the invention to operate around 800 MHZhas a substantially flat response (i.e., plus or minus a few dB of power) from 100 MHZ to 1 GHZ. This is referred to herein as a wide-band receiver; and
a receiver built in accordance with the inventioncan include multiple, user-selectable, Impedance match modules, each designed for a different wide-band of frequencies, which can be used to scan an ultra-wide-band of frequencies.
the inventiondown-converts an EM signal to an IF signal by under-sampling the EM signal. This embodiment is illustrated by 4508 in FIG. 45 B.
This embodimentcan be implemented with modulated and unmodulated EM signals.
This embodimentis described herein using the modulated carrier signal F MC in FIG. 1, as an example.
the modulated carrier signal F MCis down-converted to an IF signal F IF .
the IF signal F IFcan then be demodulated, with any conventional demodulation technique to obtain a demodulated baseband signal F DMB .
the inventioncan be implemented to down-convert any EM signal, including but not limited to, modulated carrier signals and unmodulated carrier signals.
This sectionprovides a high-level description of down-converting an EM signal to an IF signal F IF , according to the invention.
an operational process of under-sampling a modulated carrier signal F MC to down-convert it to the IF signal F IFis described at a high-level.
a structural implementation for implementing this processis described at a high-level. This structural implementation is described herein for illustrative purposes, and is not limiting. In particular, the process described in this section can be achieved using any number of structural implementations, one of which is described in this section. The details of such structural implementations will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.
FIG. 14Bdepicts a flowchart 1407 that illustrates an exemplary method for under-sampling an EM signal to down-convert the EM signal to an intermediate signal F IF .
the exemplary method illustrated in the flowchart 1407is an embodiment of the flowchart 1401 in FIG. 14 A.
the digital AM carrier signal 616is used to illustrate a high level operational description of the invention. Subsequent sections provide detailed flowcharts and descriptions for AM, FM and PM example embodiments. Upon reading the disclosure and examples therein, one skilled in the relevant art(s) will understand that the invention can be implemented to down-convert any type of EM signal, including any form of modulated carrier signal and unmodulated carrier signals.
FIG. 15Aillustrates a portion 1510 of the AM carrier signal 616 , between time t1 and t2, on an expanded time scale.
Step 1408The process begins at step 1408 , which includes receiving an EM signal.
Step 1408is represented by the digital AM carrier signal 616 .
Step 1410includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 15Billustrates an example under-sampling signal 1502 , which includes a train of pulses 1504 having negligible apertures that tend toward zero time in duration. The pulses 1504 repeat at the aliasing rate, or pulse repetition rate. Aliasing rates are discussed below.
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to the intermediate signal F IF .
the frequency or aliasing rate of the pulses 1504sets the IF.
FIG. 15Cillustrates a stair step AM intermediate signal 1506 , which is generated by the down-conversion process.
the AM intermediate signal 1506is similar to the AM carrier signal 616 except that the AM intermediate signal 1506 has a lower frequency than the AM carrier signal 616 .
the AM carrier signal 616has thus been down-converted to the AM intermediate signal 1506 .
the AM intermediate signal 1506can be generated at any frequency below the frequency of the AM carrier signal 616 by adjusting the aliasing rate.
FIG. 15Ddepicts the AM intermediate signal 1506 as a filtered output signal 1508 .
the inventionoutputs a stair step, non-filtered or partially filtered output signal.
the choice between filtered, partially filtered and non-filtered output signalsis generally a design choice that depends upon the application of the invention.
the intermediate frequency of the down-converted signal F IFwhich in this example is the AM intermediate signal 1506 , can be determined from EQ. (2), which is reproduced below for convenience.
a suitable aliasing rate F ARcan be determined in a variety of ways.
An example method for determining the aliasing rate F ARis provided below. After reading the description herein, one skilled in the relevant art(s) will understand how to determine appropriate aliasing rates for EM signals, including ones in addition to the modulated carrier signals specifically illustrated herein.
a flowchart 1701illustrates an example process for determining an aliasing rate F AR . But a designer may choose, or an application may dictate, that the values be determined in an order that is different than the illustrated order.
the processbegins at step 1702 , which includes determining, or selecting, the frequency of the EM signal.
the frequency of the FM carrier signal 616can be, for example, 901 MHZ.
Step 1704includes determining, or selecting, the intermediate frequency. This is the frequency to which the EM signal will be down-converted.
the intermediate frequencycan be determined, or selected, to match a frequency requirement of a down-stream demodulator.
the intermediate frequencycan be, for example, 1 MHZ.
Step 1706includes determining the aliasing rate or rates that will down-convert the EM signal to the IF specified in step 1704 .
EQ. (2)can be rewritten as EQ. (3):
n•F ARF C ⁇ F IF EQ. (3)
nF C ⁇ F IF F AR EQ . ⁇ ( 4 ) or as EQ. (5):
F ARF C ⁇ F IF n EQ . ⁇ ( 5 )
F C ⁇ F IF(F C ⁇ F IF ) can be defined as a difference value F DIFF , as illustrated in EQ. (6):
EQ. (4)can be rewritten as EQ. (7):
nF DIFF F AR EQ . ⁇ ( 7 )
EQs. (2) through (7)can be solved for any valid n.
a suitable ncan be determined for any given difference frequency F DIFF and for any desired aliasing rate F AR(Desired) .
EQs. (2) through (7)can be utilized to identify a specific harmonic closest to a desired aliasing rate F AR(Desired) that will generate the desired intermediate signal F IF .
the desired aliasing rate F AR(Desired)can be, for example, 140 MHZ.
the carrier frequencyis 901 MHZ and the IF is 1 MHZ
under-sampling a 901 MHZ EM carrier signal at 150 MHZgenerates an intermediate signal at 1 MHZ.
the under-sampled EM carrier signalis a modulated carrier signal
the intermediate signalwill also substantially include the modulation.
the modulated intermediate signalcan be demodulated through any conventional demodulation technique.
a list of suitable aliasing ratescan be determined from the modified form of EQ. (5), by solving for various values of n.
Example solutionsare listed below.
900 MHZ/1900 MHZ (i.e., fundamental frequency, illustrated in FIG. 25B as 2504 );
900 MHZ/2450 MHZ (i.e., second sub-harmonic, illustrated in FIG. 25C as 2506 );
900 MHZ/3300 MHZ (i.e., third sub-harnonic, illustrated in FIG. 25D as 2508 );
900 MHZ/4225 MHZ (i.e., fourth sub-harmonic, illustrated in FIG. 25E as 2510 );
the inventiondown-converts an EM signal to a relatively standard IF in the range of, for example, 100 KHZ to 200 MHZ.
the inventiondown-converts an EM signal to a relatively low frequency of, for example, less than 100 KHZ.
the inventiondown-converts an EM signal to a relatively higher IF signal, such as, for example, above 200 MHZ.
the various off-set implementationsprovide selectivity for different applications.
lower data rate applicationscan operate at lower intermediate frequencies.
higher intermediate frequenciescan allow more information to be supported for a given modulation technique.
a designerpicks an optimum information bandwidth for an application and an optimum intermediate frequency to support the baseband signal.
the intermediate frequencyshould be high enough to support the bandwidth of the modulating baseband signal F MB .
the frequency of the down-onverted IF signaldecreases.
the IFincreases.
Aliased frequenciesoccur above and below every harmonic of the aliasing frequency.
the IF of interestis preferably not near one half the aliasing rate.
an aliasing moduleincluding a universal frequency translator (UFT) module built in accordance with the invention, provides a wide range of flexibility in frequency selection and can thus be implemented in a wide range of applications.
UFTuniversal frequency translator
FIG. 16illustrates a block diagram of an under-sampling system 1602 according to an embodiment of the invention.
the under-sampling system 1602is an example embodiment of the generic aliasing system 1302 in FIG. 13 .
the under-sampling system 1602includes an under-sampling module 1606 .
the under-sampling module 1606receives the EM signal 1304 and an under-sampling signal 1604 , which includes under-sampling pulses having negligible apertures that tend towards zero time, occurring at a frequency equal to the aliasing rate F AR .
the under-sampling signal 1604is an example embodiment of the aliasing signal 1310 .
the under-sampling module 1606under-samples the EM signal 1304 at the aliasing rate F AR of the under-sampling signal 1604 .
the under-sampling system 1602outputs a down-converted signal 1308 A.
the under-sampling module 1606under-samples the EM signal 1304 to down-convert it to the intermediate signal F IF in the manner shown in the operational flowchart 1407 of FIG. 14 B.
the scope and spirit of the inventionincludes other structural embodiments for performing the steps of the flowchart 1407 .
the specifics of the other structural embodimentswill be apparent to persons skilled in the relevant art(s) based on the discussion contained herein.
the aliasing rate F AR of the under-sampling signal 1604is chosen in the manner discussed in Section II.1.1.1 so that the under-sampling module 1606 under-samples the EM carrier signal 1304 generating the intermediate frequency F IF .
the under-sampling module 1606receives the AM signal 616 (FIG. 15 A).
the under-sampling module 1606receives the under-sampling signal 1502 (FIG. 15 B).
the under-sampling module 1606under-samples the AM carrier signal 616 at the aliasing rate of the under-sampling signal 1502 , or a multiple thereof, to down-convert the AM carrier signal 616 to the intermediate signal 1506 (FIG. 15 D).
Example implementations of the under-samnpling module 1606are provided in Sections 4 and 5 below.
the method for down-converting the EM signal 1304 to the intermediate signal F IFcan be implemented with any type of EM signal, including unmodulated EM carrier signals and modulated carrier signals including, but not limited. to, AM, FM, PM, etc., or any combination thereof. Operation of the flowchart 1407 of FIG. 14B is described below for AM, FM and PM carrier signals. The exemplary descriptions below are intended to facilitate an understanding of the present invention. The present invention is not limited to or by the exemplary embodiments below.
FIG. 19AA process for down-converting the analog AM carrier signal 516 in FIG. 5C to an analog AM intermediate signal is now described with reference to the flowchart 1407 in FIG. 14 B.
the analog AM carrier signal 516is re-illustrated in FIG. 19A for convenience.
the analog AM carrier signal 516oscillates at approximately 901 MHZ.
FIG. 19Ban analog AM carrier signal 1904 illustrates a portion of the analog AM carrier signal 516 on an expanded time scale.
step 1408which includes receiving tie EM signal. This is represented by the analog AM carrier signal 516 in FIG. 19 A.
Step 1410includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 19Cillustrates an example under-sampling signal 1906 on approximately the same time scale as FIG. 19 B.
the under-sampling signal 1906includes a train of pulses 1907 having negligible apertures that tend towards zero time in duration.
the pulses 1907repeat at the aliasing rate, or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the difference frequency F DIFF .
the aliasing rateis approximately 450 MHZ.
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to the intermediate signal F IF .
Step 1412is illustrated in FIG. 19B by under-sample points 1905 .
the under-sample points 1905“walk through” the analog AM carrier signal 516 .
the under-sample points 1905“walk through” the analog AM carrier signal 516 at approximately a one megahertz rate.
the under-sample points 1905occur at different locations on subsequent cycles of the AM carrier signal 516 .
the under-sample points 1905capture varying amplitudes of the analog AM signal 516 .
under-sample point 1905 Ahas a larger amplitude than under-sample point 1905 B.
the under-sample points 1905correlate to voltage points 1908 .
the voltage points 1908form an analog AM intermediate signal 1910 . This can be accomplished in many ways. For example, each voltage point 1908 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as discussed below.
an AM intermediate signal 1912represents the AM intermediate signal 1910 , after filtering, on a compressed time scale.
FIG. 19Eillustrates the AM intermediate signal 1912 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the AM intermediate signal 1912is substantially similar to the AM carrier signal 516 , except that the AM intermediate signal 1912 is at the 1 MHZ intermediate frequency.
the AM intermediate signal 1912can be demodulated through any conventional AM demodulation technique.
the AM intermediate signal 1910 in FIG. 19 D and the AM intermediate signal 1912 in FIG. 19Eillustrate that the AM carrier signal 516 was successfully down-converted to an intermediate signal by retaining enough baseband information for sufficient reconstruction.
FIG. 18AA process for down-converting the digital AM carrier signal 616 in FIG. 6C to a digital AM intermediate signal is now described with reference to the flowchart 1407 in FIG. 14 B.
the digital AM carrier signal 616is re-illustrated in FIG. 18A for convenience.
the digital AM carrier signal 616oscillates at approximately 901 MHZ.
an AM carrier signal 1804illustrates aportion of the AM signal 616 , from time t0 to t1, on an expanded time scale.
step 1408The process begins at step 1408 , which includes receiving an EM signal. This is represented by the AM signal 616 in FIG. 18 A.
Step 1410includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 18Cillustrates an example under-sampling signal 1806 on approximately the same time scale as FIG. 18 B.
the under-sampling signal 1806includes a train of pulses 1807 having negligible apertures that tend towards zero time in duration.
the pulses 1807repeat at the aliasing rate, or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the difference frequency F DIFF .
the aliasing rateis approximately 450 MHZ.
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to the intermediate signal F IF .
Step 1412is illustrated in FIG. 18B by under-sample points 1805 .
the under-sample points 1805walk through the AM carrier signal 616 .
the under-sample points 1805occur at different locations of subsequent cycles of the AM signal 616 .
the under-sample points 1805capture various amplitudes of the AM signal 616 .
the under-sample points 1805walk through the AM carrier signal 616 at approximately a 1 MHZ rate.
under-sample point 1805 Ahas a larger amplitude than under-sample point 1805 B.
the under-sample points 1805correlate to voltage points 1808 .
the voltage points 1805form an AM intermediate signal 1810 .
each voltage point 1808can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as discussed below.
an AM intermediate signal 1812represents the AM intermediate signal 1810 , afterfiltering, on acompressed time scale.
FIG. 18Eillustrates the AM intermediate signal 1812 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the AM intermediate signal 1812is substantially similar to the AM carrier signal 616 , except that the AM intermediate signal 1812 is at the 1 MHZ intermediate frequency.
the AM intermediate signal 1812can be demodulated through any conventional AM demodulation technique.
the AM intermediate signal 1810 in FIG. 18 D and the AM intermediate signal 1812 in FIG. 18Eillustrate that the AM carrier signal 616 was successfully down-converted to an intermediate signal by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the AM carrier signal 516 (FIG. 19 A).
the under-sampling module 1606receives the under-sampling signal 1906 (FIG. 19 C).
the under-sampling module 1606under-samples the AM carrier signal 516 at the aliasing rate of the under-sampling signal 1906 to down-conved it to the AM intermediate signal 1912 (FIG. 19 E).
the under-sampling module 1606receives the AM carrier signal 616 (FIG. 18 A).
the under-sampling module 1606receives the under-sampling signal 1806 (FIG. 18 C).
the under-sampling module 1606under-samples the AM carrier signal 616 at the aliasing rate of the under-sampling signal 1806 to down-convert it to the AM intermediate signal 1812 (FIG. 18 E).
Example implementations of the under-sampling module 1606are provided in Sections 4 and 5 below.
FIG. 20AA process for down-converting the analog FM carrier signal 716 to an analog FM intermediate signal is now described with reference to the flowchart 1407 in FIG. 14 B.
the analog FM carrier signal 716is re-illustrated in FIG. 20A for convenience.
the analog FM carrier signal 716oscillates at approximately 901 MHZ.
an FM carrier signal 2004illustrates a portion of the analog FM carrier signal 716 , from time t1 to t3, on an expanded time scale.
the processbegins at step 1408 , which includes receiving an EM signal. This is represented in FIG. 20A by the FM carrier signal 716 .
Step 1410includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 20Cillustrates an example under-sampling signal 2006 on approximately the same time scale as FIG. 20 B.
the under-sampling signal 2006includes a train of pulses 2007 having negligible apertures that tend towards zero time in duration.
the pulses 2007repeat at the aliasing rate or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the difference frequency F DIFF .
the FM carrier signal 716is centered around 901 MHZ
the aliasing rateis approximately 450 MHZ.
Step 1412includes under-sampling the EM signal at the aliasing rate to downconvert the EM signal to the intermediate signal F IF .
Step 1412is illustrated in FIG. 20B by under-sample points 2005 .
the under-sample points 2005occur at different locations of subsequent cycles of the under-sampled signal 716 . In other words, the under-sample points 2005 walk through the signal 716 . As a result, the under-sample points 2005 capture various amplitudes of the FM carrier signal 716 .
the under-sample points 2005correlate to voltage points 2008 .
the voltage points 2005form an analog FM intermediate signal 2010 .
each voltage point 2008can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as discussed below.
an FM intermediate signal 2012illustrates the FM intermediate signal 2010 , after filtering, on a compressed time scale.
FIG. 20Eillustrates the FM intermediate signal 2012 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the FM intermediate signal 2012is substantially similar to the FM carrier signal 716 , except that the FM intermediate signal 2012 is at the 1 MHZ intermediate frequency.
the FM intermediate signal 2012can be demodulated through any conventional FM demodulation technique.
the drawings referred to hereinillustrate frequency down-conversion in accordance with the invention.
the FM intermediate signal 2010 in FIG. 20 D and the FM intermediate signal 2012 in FIG. 20Eillustrate that the FM carrier signal 716 was successfully down-converted to an intermediate signal by retaining enough baseband information for sufficient reconstruction.
FIG. 21AA process for down-converting the digital FM carrier signal 816 to a digital FM intermediate signal is now described with reference to the flowchart 1407 in FIG. 14 B.
the digital FM carrier signal 816is re-illustrated in FIG. 21A for convenience.
the digital FM carrier signal 816oscillates at approximately 901 MHZ.
an FM carrier signal 2104illustrates a portion of the FM carrier signal 816 , from time t1 to t3, on an expanded time scale.
step 1408which includes receiving an EM signal. This is represented in FIG. 21A, by the FM carrier signal 816 .
Step 1410includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 21Cillustrates an example under-sampling signal 2106 on approximately the same time scale as FIG. 21 B.
the under-sampling signal 2106includes a train of pulses 2107 having negligible apertures that tend toward zero time in duration.
the pulses 2107repeat at the aliasing rate, or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the difference frequency F DIFF .
the aliasing rateis selected as approximately 450 MHZ, which is a sub-harmonic of 900 MHZ, which is off-set by 1 MHZ from the center frequency of the FM carrier signal 816 .
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to an intermediate signal F IF .
Step 1412is illustrated in FIG. 21B by under-sample points 2105 .
the under-sample points 2105occur at different locations of subsequent cycles of the FM carrier signal 816 . In other words, the under-sample points 2105 walk through the signal 816 . As a result, the under-sample points 2105 capture various amplitudes of the signal 816 .
the under-sample points 2105correlate to voltage points 2108 .
the voltage points 2108form a digital FM intermediate signal 2110 . This can be accomplished in many ways. For example, each voltage point 2108 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
an FM intermediate signal 2112represents the FM intermediate signal 2110 , after filtering, on acompressed time scale.
FIG. 21Eillustrates the FM intermediate signal 2112 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the FM intermediate signal 2112is substantially similar to the FM carrier signal 816 , except that the FM intermediate signal 2112 is at the 1 MHZ intermediate frequency.
the FM intermediate signal 2112can be demodulated through any conventional FM demodulation technique.
the drawings referred to hereinillustrate frequency down-conversion in accordance with the invention.
the FM intermediate signal 2110 in FIG. 21 D and the FM intermediate signal 2112 in FIG. 21Eillustrate that the FM carrier signal 816 was successfully down-converted to an intermediate signal by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the FM carrier signal 716 (FIG. 20 A).
the under-sampling module 1606receives the under-sampling signal 2006 (FIG. 20 C).
the under-sampling module 1606under-samples the FM carrier signal 716 at the aliasing rate of the under-sampling signal 2006 to down-convert the FM carrier signal 716 to the FM intermediate signal 2012 (FIG. 20 E).
the under-sampling module 1606receives the FM carrier signal 816 (FIG. 21 A).
the under-sampling module 1606receives the under-sampling signal 2106 (FIG. 21 C).
the under-sampling module 1606under-samples the FM carrier signal 816 at the aliasing rate of the under-sampling signal 2106 to down-convert the FM carrier signal 816 to the FM intermediate signal 2112 (FIG. 21 E).
Example implementations of the under-sampling module 1606are provided in Sections 4 and 5 below.
FIG. 23AA process for down-converting the analog PM carrier signal 916 to an analog PM intermediate signal is now described with reference to the flowchart 1407 in FIG. 14 B.
the analog PM carrier signal 916is re-illustrated in FIG. 23A for convenience.
the analog PM carrier signal 916oscillates at approximately 901 MHZ.
a PM carrier signal 2304illustrates a portion of the analog PM carrier signal 916 , from time t1 to t3, on an expanded time scale.
the process of down-converting the PM carrier signal 916 to a PM intermediate signalbegins at step 1408 , which includes receiving an EM signal. This is represented in FIG. 23A, by the analog PM carrier signal 916 .
Step 1410includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 23Cillustrates an example under-sampling signal 2306 on approximately the same time scale as FIG. 23 B.
the under-sampling signal 2306includes a train of pulses 2307 having negligible apertures that tend towards zero time in duration.
the pulses 2307repeat at the aliasing rate, or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the difference frequency F DIFF .
the aliasing rateis approximately 450 MHZ.
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to the intermediate signal F IF .
Step 1412is illustrated in FIG. 23B by under-sample points 2305 .
the under-sample points 2305occur at different locations of subsequent cycles of the PM carrier signal 916 .
the under-sample pointscapture various amplitudes of the PM carrier signal 916 .
voltage points 2308correlate to the under-sample points 2305 .
the voltage points 2308form an analog PM intermediate signal 2310 . This can be accomplished in many ways. For example, each voltage point 2308 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
an analog PM intermediate signal 2312illustrates the analog PM intermediate signal 2310 , after filtering, on a compressed time scale.
FIG. 23Eillustrates the PM intermediate signal 2312 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the analog PM intermediate signal 2312is substantially similar to the analog PM carrier signal 916 , except that the analog PM intermediate signal 2312 is at the 1 MHZ intermediate frequency.
the analog PM intermediate signal 2312can be demodulated through any conventional PM demodulation technique.
FIG. 23 D and the analog PM intermediate signal 2312 in FIG. 23Eillustrate that the analog PM carrier signal 2316 was successfully down-converted to an intermediate signal by retaining enough baseband information for sufficient reconstruction.
a process for down-converting the digital PM carrier signal 1016 to a digital PM intermediate signalis now described with reference to the flowchart 1407 in FIG. 14 B.
the digital PM carrier signal 1016is re-illustrated in FIG. 22A for convenience.
the digital PM carrier signal 1016oscillates at approximately 901 MHZ.
a PM carrier signal 2204illustrates a portion of the digital PM carrier signal 1016 , from time t1 to t3, on an expanded time scale.
step 1408which includes receiving an EM signal. This is represented in FIG. 22A by the digital PM carrier signal 1016 .
Step 1408includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 22Cillustrates example under-sampling signal 2206 on approximately the same time scale as FIG. 22 B.
the under-sampling signal 2206includes a train of pulses 2207 having negligible apertures that tend towards zero time in duration.
the pulses 2207repeat at the aliasing rate, or a pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the difference frequency F DIFF .
the aliasing rateis approximately 450 MHZ.
Step 1412includes under-sampling the EM signal at the aliasing rate to down-convert the EM signal to an intermediate signal F IF .
Step 1412is illustrated in FIG. 22B by under-sample points 2205 .
the under-sample points 2205occur at different locations of subsequent cycles of the PM carrier signal 1016 .
voltage points 2208correlate to the under-sample points 2205 .
the voltage points 2208form a digital PM intermediate signal 2210 . This can be accomplished in many ways. For example, each voltage point 2208 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
a digital PM intermediate signal 2212represents the digital PM intermediate signal 2210 on a compressed time scale.
FIG. 22Eillustrates the PM intermediate signal 2212 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the digital PM intermediate signal 2212is substantially similar to the digital PM carrier signal 1016 , except that the digital PM intermediate signal 2212 is at the 1 MHZ intermediate frequency.
the digital PM carrier signal 2212can be demodulated through any conventional PM demodulation technique.
FIG. 22 D and the digital PM intermediate signal 2212 in FIG. 22Eillustrate that the digital PM carrier signal 1016 was successfully down-converted to an intermediate signal by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the PM carrier signal 916 (FIG. 23 A).
the under-sampling module 1606receives the under-sampling signal 2306 (FIG. 23 C).
the under-sampling module 1606under-samples the PM carrier signal 916 at the aliasing rate of the under-sampling signal 2306 to down-convert the PM carrier signal 916 to the PM intermediate signal 2312 (FIG. 23 E).
the under-sampling module 1606receives the PM carrier signal 1016 (FIG. 22 A).
the under-sampling module 1606receives the under-sampling signal 2206 (FIG. 22 C).
the under-sampling module 1606under-samples the PM carrier signal 1016 at the aliasing rate of the under-sampling signal 2206 to down-convert the PM carrier signal 1016 to the PM intermediate signal 2212 (FIG. 22 E).
Example implementations of the under-sampling module 1606are provided in Sections 4 and 5 below.
the inventiondirectly down-converts an EM signal to a baseband signal, by under-sampling the EM signal.
This embodimentis referred to herein as direct-to-data down-conversion and is illustrated in FIG. 45B as 4510 .
This embodimentcan be implemented with modulated and unmodulated EM signals.
This embodimentis described herein using the modulated carrier signal F MC in FIG. 1, as an example.
the modulated carrier signal F MCis directly down-converted to the demodulated baseband signal F DMB .
the inventionis applicable to down-convert any EM signal, including but not limited to, modulated carrier signals and unmodulated carrier signals.
This sectionprovides a high-level description of directly down-converting the modulated carrier signal F MC to the demodulated baseband signal F DMB , according to the invention.
an operational process of directly down-converting the modulated carrier signal F MC to the demodulated baseband signal F DMBis described at a high-level.
a structural implementation for implementing this processis described at a high-level.
the structural implementationis described herein for illustrative purposes, and is not limiting.
the process described in this sectioncan be achieved using any number of structural implementations, one of which is described in this section. The details of such structural implementations will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.
FIG. 14Cdepicts a flowchart 1413 that illustrates an exemplary method for directly down-converting an EM signal to a demodulated baseband signal F DMB .
the exemplary method illustrated in the flowchart 1413is an embodiment of the flowchart 1401 in FIG. 14 A.
the digital AM carrier signal 616is used to illustrate a high level operational description of the invention. Subsequent sections provide detailed descriptions for AM and PM example embodiments. FM presents special considerations that are dealt with separately in Section II.3, below. Upon reading the disclosure and examples therein, one skilled in the relevant art(s) will understand that the invention can be implemented to down-convert any type of EM signal, including any form of modulated carrier signal and unmodulated carrier signals.
the method illustrated in the flowchart 1413is now described at a high level using the digital AM carrier signal 616 , from FIG. 6 C.
the digital AM carrier signal 616is re-illustrated in FIG. 33A for convenience.
Step 1414The process of the flowchart 1413 begins at step 1414 , which includes receiving an EM signal.
Step 1414is represented by the digital AM carrier signal 616 in FIG. 33 A.
Step 1416includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 33Billustrates an example under-sampling signal 3302 which includes a train of pulses 3303 having negligible apertures that tend towards zero time in duration. The pulses 3303 repeat at the aliasing rate or pulse repetition rate. The aliasing rate is determined in accordance with EQ. (2), reproduced below for convenience.
the aliasing rateis substantially equal to the frequency of the AM signal 616 or to a harmonic or sub-harmonic thereof.
the aliasing rateis too low to permit reconstruction of higher frequency components of the AM signal 616 (i.e., the carrier frequency), it is high enough to permit substantial reconstruction of the lower frequency modulating baseband signal 310 .
Step 1418includes under-sampling the EM signal at the aliasing rate to directly down-convert it to the demodulated baseband signal F DMB .
FIG. 33Cillustrates a stair step demodulated baseband signal 3304 , which is generated by the direct down-conversion process.
the demodulated baseband signal 3304is similar to the digital modulating baseband signal 310 in FIG. 3 .
FIG. 33Ddepicts a filtered demodulated baseband signal 3306 , which can be generated from the stair step demodulated baseband signal 3304 .
the inventioncan thus generate a filtered output signal, a partially filtered output signal, or a relatively unfiltered stair step output signal.
the choice between filtered, partially filtered and non-filtered output signalsis generally a design choice that depends upon the application of the invention.
FIG. 16illustrates the block diagram of the under-sampling system 1602 according to an embodiment of the invention.
the under-sampling system 1602is an example embodiment of the generic aliasing system 1302 in FIG. 13 .
the frequency of the under-sampling signal 1604is substantially equal to a harmonic of the EM signal 1304 or, more typically, a sub-harmonic thereof.
the under-sampling module 1606under-samples the EM signal 1304 to directly down-convert it to the demodulated baseband signal F DMB , in the manner shown in the operational flowchart 1413 .
the scope and spirit of the inventionincludes other structural embodiments for performing the steps of the flowchart 1413 . The specifics of the other structural embodiments will be apparent to persons skilled in the relevant art(s) based on the discussion contained herein.
the under-sampling module 1606receives the AM carrier signal 616 (FIG. 33 A).
the under-sampling module 1606receives the under-sampling signal 3302 (FIG. 33 B).
the under-sampling module 1606under-samples the AM carrier signal 616 at the aliasing rate of the under-sampling signal 3302 to directly down-convert the AM carrier signal 616 to the demodulated baseband signal 3304 in FIG. 33C or the filtered demodulated baseband signal 3306 in FIG. 33 D.
Example implementations of the under-sampling module 1606are provided in Sections 4 and 5 below.
the method for down-converting the EM signal 1304 to the demodulated baseband signal F DMBcan be implemented with any type EM signal, including modulated carrier signals, including but not limited to, AM, PM, etc., or any combination thereof. Operation of the flowchart 1413 of FIG. 14C is described below for AM and PM carrier signals. The exemplary descriptions below are intended to facilitate an understanding of the present invention. The present invention is not limited to or by the exemplary embodiments below.
a process for directly down-converting the analog AM carrier signal 516 to a demodulated baseband signalis now described with reference to the flowchart 1413 in FIG. 14 C.
the analog AM carrier signal 516is re-illustrated in 35 A for convenience.
the analog AM carrier signal 516oscillates at approximately 900 MHZ.
an analog AM carrier signal 3504illustrates a portion of the analog AM carrier signal 516 on an expanded time scale.
the processbegins at step 1414 , which includes receiving an EM signal. This is represented by the analog AM carrier signal 516 .
Step 1416includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 35Cillustrates an example under-sampling signal 3506 on approximately the same time scale as FIG. 35 B.
the under-sampling signal 3506includes a train of pulses 3507 having negligible apertures that tend towards zero time in duration.
the pulses 3507repeat at the aliasing rate or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the under-sampled signal. In this example, the aliasing rate is approximately 450 MHZ.
Step 1418includes under-sampling the EM signal at the aliasing rate to directly down-convert it to the demodulated baseband signal F DMB .
Step 1418is illustrated in FIG. 35B by under-sample points 3505 . Because a harmonic of the aliasing rate is substantially equal to the frequency of the signal 516 , essentially no IF is produced. The only substantial aliased component is the baseband signal.
voltage points 3508correlate to the under-sample points 3505 .
the voltage points 3508form a demodulated baseband signal 3510 . This can be accomplished in many ways. For example, each voltage point 3508 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
a demodulated baseband signal 3512represents the demodulated baseband signal 3510 , after filtering, on a compressed time scale.
FIG. 35Eillustrates the demodulated baseband signal 3512 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the demodulated baseband signal 3512is substantially similar to the modulating baseband signal 210 .
the demodulated baseband signal 3512can be processed using any signal processing technique(s) without further down-conversion or demodulation.
the aliasing rate of the under-sampling signalis preferably controlled to optimize the demodulated baseband signal for amplitude output and polarity, as desired.
the under-sample points 3505occur at positive locations of the AM carrier signal 516 .
the under-sample points 3505can occur at other locations including negative points of the analog AM carrier signal 516 .
the resultant demodulated baseband signalis inverted relative to the modulating baseband signal 210 .
the demodulated baseband signal 3510 in FIG. 35 D and the demodulated baseband signal 3512 in FIG. 35Eillustrate that the AM carrier signal 516 was successfully down-converted to the demodulated baseband signal 3510 by retaining enough baseband information for sufficient reconstruction.
FIG. 36AA process for directly down-converting the digital AM carrier signal 616 to a demodulated baseband signal is now described with reference to the flowchart 1413 in FIG. 14 C.
the digital AM carrier signal 616is re-illustrated in FIG. 36A for convenience.
the digital AM carrier signal 616oscillates at approximately 901 MHZ.
FIG. 36Ba digital AM carrier signal 3604 illustrates a portion of the digital AM carrier signal 616 on an expanded time scale.
the processbegins at step 1414 , which includes receiving an EM signal. This is represented by the digital AM carrier signal 616 .
Step 1416includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 36Cillustrates an example under-sampling signal 3606 on approximately the same time scale as FIG. 36 B.
the under-sampling signal 3606includes a train of pulses 3607 having negligible apertures that tend towards zero time in duration.
the pulses 3607repeat at the aliasing rate or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the under-sampled signal. In this example, the aliasing rate is approximately 450 MHZ.
Step 1418includes under-sampling the EM signal at the aliasing rate to directly down-convert it to the demodulated baseband signal F DMB .
Step 1418is illustrated in FIG. 36B by under-sample points 3605 . Because the aliasing rate is substantially equal to the AM carrier signal 616 , or to a harmonic or sub-harmonic thereof, essentially no IF is produced. The only substantial aliased component is the baseband signal.
voltage points 3608correlate to the under-sample points 3605 .
the voltage points 3608form a demodulated baseband signal. 3610 .
each voltage point 3608can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
a demodulated baseband signal 3612represents the demodulated baseband signal 3610 , after filtering, on a compressed time scale.
FIG. 36Eillustrates the demodulated baseband signal 3612 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the demodulated baseband signal 3612is substantially similar to the digital modulating baseband signal 310 .
the demodulated analog baseband signal 3612can be processed using any signal processing technique(s) without further down-conversion or demodulation.
the aliasing rate of the under-sampling signalis preferably controlled to optimize the demodulated baseband signal for amplitude output and polarity, as desired.
the under-sample points 3605occur at positive locations of signal portion 3604 .
the under-sample points 3605can occur at other locations including negative locations of the signal portion 3604 .
the resultant demodulated baseband signalis inverted with respect to the modulating baseband signal 310 .
the demodulated baseband signal 3610 in FIG. 36 D and the demodulated baseband signal 3612 in FIG. 36Eillustrate that the digital AM carrier signal 616 was successfully down-converted to the demodulated baseband signal 3610 by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the analog AM carrier signal 516 (FIG. 35 A).
the under-sampling module 1606receives the under-sampling signal 3506 (FIG. 35 C).
the under-sampling module 1606under-samples the analog AM carrier signal 516 at the aliasing rate of the under-sampling signal 3506 to directly to down-convert the AM carrier signal 516 to the demodulated analog baseband signal 3510 in FIG. 35D or to the filtered demodulated analog baseband signal 3512 in FIG. 35 E.
the under-sampling module 1606receives the digital AM carrier signal 616 (FIG. 36 A).
the under-sampling module 1606receives the under-sampling signal 3606 (FIG. 36 C).
the under-sampling module 1606under-samples the digital AM carrier signal 616 at the aliasing rate of the under-sampling signal 3606 to down-convert the digital AM carrier signal 616 to the demodulated digital baseband signal 3610 in FIG. 36D or to the filtered demodulated digital baseband signal 3612 in FIG. 36 E.
Example implementations of the under-sampling, module 1606are provided in Sections 4 and 5 below.
a process for directly down-converting the analog PM carrier signal 916 to a demodulated baseband signalis now described with reference to the flowchart 1413 in FIG. 14 C.
the analog PM carrier signal 916is re-illustrated in 37 A for convenience.
the analog PM carrier signal 916oscillates at approximately 900 MHZ.
an analog PM carrier signal 3704illustrates a portion of the analog PM carrier signal 916 on an expanded time scale.
the processbegins at step 1414 , which includes receiving an EM signal. This is represented by the analog PM signal 916 .
Step 1416includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 37Cillustrates an example under-sampling signal 3706 on approximately the same time scale as FIG. 37 B.
the under-sampling signal 3706includes a train of pulses 3707 having negligible apertures that tend towards zero time in duration.
the pulses 3707repeat at the aliasing rate or pulse repetition rate, which is determined or selected as previously described.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the under-sampled signal. In this example, the aliasing rate is approximately 450 MHZ.
Step 1418includes under-sampling the analog PM carrier signal 916 at the aliasing rate to directly down-convert it to a demodulated baseband signal. Step 1418 is illustrated in FIG. 37B by under-sample points 3705 .
a harmonic of the aliasing rateis substantially equal to the frequency of the signal 916 , or substantially equal to a harmonic or sub-harmonic thereof, essentially no IF is produced.
the only substantial aliased componentis the baseband signal.
voltage points 3708correlate to the under-sample points 3705 .
the voltage points 3708form a demodulated baseband signal 3710 . This can be accomplished in many ways. For example, each voltage point 3708 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
a demodulated baseband signal 3712represents the demodulated baseband signal 3710 , after filtering, on a compressed time scale.
FIG. 37Eillustrates the demodulated baseband signal 3712 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the demodulated baseband signal 3712is substantially similar to the analog modulating baseband signal 210 .
the demodulated baseband signal 3712can be processed without further down-conversion or demodulation.
the aliasing rate of the under-sampling signalis preferably controlled to optimize the demodulated baseband signal for amplitude output and polarity, as desired.
the under-sample points 3705occur at positive locations of the analog PM carrier signal 916 .
the under-sample points 3705can occur at other locations include negative points of the analog PM carrier signal 916 .
the resultant demodulated baseband signalis inverted relative to the modulating baseband signal 210 .
the demodulated baseband signal 3710 in FIG. 37 D and the demodulated baseband signal 3712 in FIG. 37Eillustrate that the analog PM carrier signal 916 was successfully down-converted to the demodulated baseband signal 3710 by retaining enough baseband information for sufficient reconstruction.
the digital PM carrier signal 1016is re-illustrated in 38 A for convenience.
the digital PM carrier signal 1016oscillates at approximately 900 MHZ.
a digital PM carrier signal 3804illustrates a portion of the digital PM carrier signal 1016 on an expanded time scale.
the processbegins at step 1414 , which includes receiving an EM signal. This is represented by the digital PM signal 1016 .
Step 1416includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 38Cillustrates an example under-sampling signal 3806 on approximately the same time scale as FIG. 38 B.
the under-sampling signal 3806includes a train of pulses 3807 having negligible apertures that tend towards zero time in duration.
the pulses 3807repeat at the aliasing rate or pulse repetition rate, which is determined or selected as described above.
the aliasing rate F ARis substantially equal to a harmonic or, more typically, a sub-harmonic of the under-sampled signal. In this example, the aliasing rate is approximately 450 MHZ.
Step 1418includes under-sampling the digital PM carrier signal 1016 at the aliasing rate to directly down-convert it to a demodulated baseband signal. This is illustrated in FIG. 38B by under-sample points 3705 .
a harmonic of the aliasing rateis substantially equal to the frequency of the signal 1016 , essentially no IF is produced.
the only substantial aliased componentis the baseband signal.
voltage points 3808correlate to the under-sample points 3805 .
the voltage points 3808form a demodulated baseband signal 3810 . This can be accomplished in many ways. For example, each voltage point 3808 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
a demodulated baseband signal 3812represents the demodulated baseband signal 3810 , after filtering, on a compressed time scale.
FIG. 38Eillustrates the demodulated baseband signal 3812 as a filtered output signal, the output signal does not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the demodulated baseband signal 3812is substantially similar to the digital modulating baseband signal 310 .
the demodulated baseband signal 3812can be processed without further down-conversion or demodulation.
the aliasing rate of the under-sampling signalis preferably controlled to optimize the demodulated baseband signal for amplitude output and polarity, as desired.
the under-sample points 3805occur at positive locations of the digital PM carrier signal 1016 .
the under-sample points 3805can occur at other locations include negative points of the digital PM carrier signal 1016 .
the resultant demodulated baseband signalis inverted relative to the modulating baseband signal 310 .
the demodulated baseband signal 3810 in FIG. 38 D and the demodulated baseband signal 3812 in FIG. 38Eillustrate that the digital PM carrier signal 1016 was successfully down-converted to the demodulated baseband signal 3810 by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the analog PM carrier signal 916 (FIG. 37 A).
the under-sampling module 1606receives the under-sampling signal 3706 (FIG. 37 C).
the under-sampling module 1606under-samples the analog PM carrier signal 916 at the aliasing rate of the under-sampling signal 3706 to down-convert the PM carrier signal 916 to the demodulated analog baseband signal 3710 in FIG. 37D or to the filtered demodulated analog baseband signal 3712 in FIG. 37 E.
the under-sampling module 1606receives the digital PM carrier signal 1016 (FIG. 38 A).
the under-sampling module 1606receives the under-sampling signal 3806 (FIG. 38 C).
the under-sampling module 1606under-samples the digital PM carrier signal 1016 at the aliasing rate of the under-sampling signal 3806 to down-convert the digital PM carrier signal 1016 to the demodulated digital baseband signal 3810 in FIG. 38D or to the filtered demodulated digital baseband signal 3812 in FIG. 38 E.
the inventiondown-converts an FM carrier signal FF MC to a non-FM signal F (NON-FM) , by under-sampling the FM carrier signal F FMC .
This embodimentis illustrated in FIG. 45B as 4512 .
the FM carrier signal F FMCis down-converted to a phase modulated (PM) signal F PM .
the FM carrier signal F FMCis down-converted to an amplitude modulated (AM) signal F AM .
the inventionis not limited to these embodiments.
the down-onverted signalcan be demodulated with any conventional demodulation technique to obtain a demodulated baseband signal F DMB .
the inventioncan be implemented with any type of FM signal. Exemplary embodiments are provided below for down-converting a frequency shift keying (FSK) signal to a non-FSK signal.
FSKis a sub-set of FM, wherein an FM signal shifts or switches between two or more frequencies.
FSKis typically used for digital modulating baseband signals, such as the digital modulating baseband signal 310 in FIG. 3 .
the digital FM signal 816is an FSK signal that shifts between an upper frequency and a lower frequency, corresponding to amplitude shifts in the digital modulating baseband signal 310 .
the FSK signal 816is used in example embodiments below.
the FSK signal 816is under-sampled at an aliasing rate that is based on a mid-point between the upper and lower frequencies of the FSK signal 816 .
the FSK signal 816is down-converted to a phase shift keying (PSK) signal.
PSKis a sub-set of phase modulation, wherein a PM signal shifts or switches between two or more phases.
PSKis typically used for digital modulating baseband signals.
the digital PM signal 1016is a PSK signal that shifts between two phases.
the PSK signal 1016can be demodulated by any conventional PSK demodulation technique(s).
the FSK signal 816is under-sampled at an aliasing rate that is based upon either the upper frequency or the lower frequency of the FSK signal 816 .
the FSK signal 816is down-converted to an amplitude shift keying (ASK) signal.
ASKis a sub-set of amplitude modulation, wherein an AM signal shifts or switches between two or more amplitudes.
ASKis typically used for digital modulating baseband signals.
the digital AM signal 616is an ASK signal that shifts between the first amplitude and the second amplitude.
the ASK signal 616can be demodulated by any conventional ASK demodulation technique(s).
This sectionprovides a high-level description of under-sampling the FM carrier signal F FM to down-convert it to the non-FM signal F (NON-FM) , according to the invention.
an operational process for down-converting the FM carrier signal F FM to the non-FM signal F (NON-FM)is described at a high-level.
a structural implementation for implementing this processis described at a high-level. The structural implementation is described herein for illustrative purposes, and is not limiting. In particular, the process described in this section can be achieved using any number of structural implementations, one of which is described in this section. The details of such structural implementations will be apparent to persons skilled in the relevant art(s) based on the teachings contained herein.
FIG. 14Ddepicts a flowchart 1419 that illustrates an exemplary method for down-converting the FM carrier signal F FMC to the non-FM signal F (NON-FM) .
the exemplary method illustrated in the flowchart 1419is an embodiment of the flowchart 1401 in FIG. 14 A.
the digital FM carrier (FSK) signal 816is used to illustrate a high level operational description of the invention. Subsequent sections provide detailed flowcharts and descriptions for the FSK signal 816 . Upon reading the disclosure and examples therein, one skilled in the relevant art(s) will understand that the invention can be implemented to down-convert any type of FM signal.
the method illustrated in the flowchart 1419is described below at a high level for down-converting the FSK signal 816 in FIG. 8C to a PSK signal.
the FSK signal 816is re-illustrated in FIG. 39A for convenience.
the process of the flowchart 1419begins at step 1420 , which includes receiving an FM signal. This is represented by the FSK signal 816 .
the FSK signal 816shifts between an upper frequency 3910 and a lower-frequency 3912 .
the upper frequency 3910is approximately 901 MHZ and the lower frequency 3912 is approximately 899 MHZ.
Step 1422includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 39Billustrates an example under-sampling signal 3902 which includes a train of pulses 3903 having negligible apertures that tend towards zero time in duration. The pulses 3903 repeat at the aliasing rate or pulse repetition rate.
the aliasing rateis substantially equal to a frequency contained within the FM signal, or substantially equal to a harmonic or sub-harmonic thereof.
the aliasing rateis based on a mid-point between the upper frequency 3910 and the lower frequency 3912 .
the mid-pointis approximately 900 MHZ.
the aliasing rateis based on either the upper frequency 3910 or the lower frequency 3912 , not the mid-point.
Step 1424includes under-sampling the FM signal F FMC at the aliasing rate to down-convert the FM carrier signal F FMC to the non-FM signal F (NON-FM) .
Step 1424is illustrated in FIG. 39C, which illustrates a stair step PSK signal 3904 , which is generated by the modulation conversion process.
the PSK signal 3904When the upper frequency 3910 is under-sampled, the PSK signal 3904 has a frequency of approximately 1 MHZ and is used as a phase reference. When the lower frequency 3912 is under-sampled, the PSK signal 3904 has a frequency of 1 MHZ and is phase shifted 180 degrees from the phase reference.
FIG. 39Ddepicts a PSK signal 3906 , which is a filtered version of the PSK signal 3904 .
the inventioncan thus generate a filtered output signal, a partially filtered output signal, or a relatively unfiltered stair step output signal.
the choice between filtered, partially filtered and non-filtered output signalsis generally a design choice that depends upon the application of the invention.
the aliasing rate of the under-sampling signalis preferably controlled to optimize the down-converted signal for amplitude output and polarity, as desired.
FIG. 16illustrates the block diagram of the under-sampling system 1602 according to an embodiment of the invention.
the under-sampling system 1602includes the under-sampling module 1606 .
the under-sampling system 1602is an example embodiment of the generic aliasing system 1302 in FIG. 13 .
the EM signal 1304is an FM carrier signal and the under-sampling module 1606 under-samples the FM carrier signal at a frequency that is substantially equal to a harmonic of a frequency within the FM signal or, more typically, substantially equal to a sub-harmonic of a frequency within the FM signal.
the under-sampling module 1606under-samples the FM carrier signal F FMC to down-convert it to a non-FM signal F (NON-FM) in the manner shown in the operational flowchart 1419 .
NON-FMnon-FM
the under-sampling module 1606receives the FSK signal 816 .
the under-sampling module 1606receives the under-sampling signal 3902 .
the under-sampling module 1606under-samples the FSK signal 816 at the aliasing rate of the under-sampling signal 3902 to down-convert the FSK signal 816 to the PSK signal 3904 or 3906 .
Example implementations of the under-sampling module 1606are provided in Section 4 below.
the method for down-converting an FM carrier signal F FMC to a non-FM signal, F (NON-FM)can be implemented with any type of FM carrier signal including, but not limited to, FSK signals.
the flowchart 1419is described in detail below for down-converting an FSK signal to a PSK signal and for down-converting an PSK signal to an FSK signal.
the exemplary descriptions beloware intended to facilitate an understanding of the present invention. The present invention is not limited to or by the exemplary embodiments below.
the FSK signal 816shifts between a first frequency 4006 and a second frequency 4008 .
the first frequency 4006is lower than the second frequency 4008 .
the first frequency 4006is higher than the second frequency 4008 .
the first frequency 4006is approximately 899 MHZ and the second frequency 4008 is approximately 901 MHZ.
FIG. 40Billustrates an FSK signal portion 4004 that represents a portion of the FSK signal 816 on an expanded time scale.
the process of down-converting the FSK signal 816 to a PSK signalbegins at step 1420 , which includes receiving an FM signal. This is represented by the FSK signal 816 .
Step 1422includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 40Cillustrates an example under-sampling signal 4007 on approximately the same time scale as FIG. 40 B.
the under-sampling signal 4007includes a train of pulses 4009 having negligible apertures that tend towards zero time in duration.
the pulses 4009repeat at the aliasing rate, which is determined or selected as described above.
the aliasing rateis substantially equal to a harmonic or, more typically, a sub-harmonic of a frequency contained within the FM signal.
the aliasing rateis substantially equal to a harmonic of the mid-point between the frequencies 4006 and 4008 or, more typically, substantially equal to a sub-harmonic of the mid-point between the frequencies 4006 and 4008 .
the mid-pointis approximately 900 MHZ
Suitable aliasing ratesinclude 1.8 GHZ, 900 MHZ, 450 MHZ, etc.
the aliasing rate of the under-sampling signal 4008is approximately 450 MHZ.
Step 1424includes under-sampling the FM signal at the aliasing rate to down-convert it to the non-FM signal F (NON-FM) .
Step 1424is illustrated in FIG. 40B by under-sample points 4005 .
the under-sample points 4005occur at the aliasing rate of the pulses 4009 .
voltage points 4010correlate to the under-sample points 4005 .
the voltage points 4010form a PSK signal 4012 . This can be accomplished in many ways. For example, each voltage point 4010 can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
the PSK signal 4012When the first frequency 4006 is under-sampled, the PSK signal 4012 has a frequency of approximately 1 MHZ and is used as a phase reference. When the second frequency 4008 is under-sampled, the PSK signal 4012 has a frequency of 1 MHZ and is phase shifted 180 degrees from the phase reference.
a PSK signal 4014illustrates the PSK signal 4012 , after filtering, on a compressed time scale.
FIG. 40Eillustrates the PSK signal 4012 as a filtered output signal 4014
the output signaldoes not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the PSK signal 4014can be demodulated through any conventional phase demodulation technique.
the aliasing rate of the under-sampling signalis preferably controlled to optimize the down-converted signal for amplitude output and polarity, as desired.
the under-sample points 4005occur at positive locations of the FSK signal 816 .
the under-sample points 4005can occur at other locations including negative points of the FSK signal 816 .
the resultant PSK signalis inverted relative to the PSK signal 4014 .
FIG. 40Eillustrates that the FSK signal 816 was successfully down-converted to the PSK signal 4012 and 4014 by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the FSK signal 816 (FIG. 40 A).
the under-sampling module 1606receives the under-sampling signal 4007 (FIG. 40 C).
the under-sampling module 1606under-samples the FSK signal 816 at the aliasing rate of the under-sampling signal 4007 to down-convert the FSK signal 816 to the PSK signal 4012 in FIG. 40D or the PSK signal 4014 in FIG. 40 E.
FIG. 14DOperation of the exemplary process of FIG. 14D is now described for down-converting the FSK signal 816 , illustrated in FIG. 8C, to an ASK signal.
the FSK signal 816is re-illustrated in FIG. 41A for convenience.
the FSK signal 816shifts between a first frequency 4106 and a second frequency 4108 .
the first frequency 4106is lower than the second frequency 4108 .
the first frequency 4106is higher than the second frequency 4108 .
the first frequency 4106is approximately 899 MHZ and the second frequency 4108 is approximately 901 MHZ.
FIG. 41Billustrates an FSK signal portion 4104 that represents a portion of the FSK signal 816 on an expanded time scale.
the process of down-converting the FSK signal 816 to an ASK signalbegins at step 1420 , which includes receiving an FM signal. This is represented by the FSK signal 816 .
Step 1422includes receiving an under-sampling signal having an aliasing rate F AR .
FIG. 41Cillustrates an example under-sampling signal 4107 illustrated on approximately the same time scale as FIG. 42 B.
the under-sampling signal 4107includes a train of pulses 4109 having negligible apertures that tend towards zero time in duration.
the pulses 4109repeat at the aliasing rate, or pulse repetition rate.
the aliasing rateis determined or selected as described above.
the aliasing ratewhen down-converting an FM signal to a non-FM signal, is substantially equal to a harmonic of a frequency within the FM signal or, more typically, to a sub-harmonic of a frequency within the FM signal.
the aliasing rateis substantially equal to a harmonic of the first frequency 4106 or the second frequency 4108 or, more typically, substantially equal to a sub-harmonic of the first frequency 4106 or the second frequency 4108 .
the aliasing ratecan be substantially equal to a harmonic or sub-harmonic of 899 MHZ or 901 MHZ.
the aliasing rateis approximately 449.5 MHZ, which is a sub-harmonic of the first frequency 4106 .
Step 1424includes under-sampling the FM signal at the aliasing rate to down-convert it to a non-FM signal F (NON-FM) .
Step 1424is illustrated in FIG. 41B by under-sample points 4105 .
the under-sample points 4105occur at the aliasing rate of the pulses 4109 .
the aliasing pulses 4109 and the under-sample points 4105occur at the same location of subsequent cycles of the FSK signal 816 . This generates a relatively constant output level.
voltage points 4110correlate to the under-sample points 4105 .
the voltage points 4110form an ASK signal 4112 .
each voltage point 41110can be held at a relatively constant level until the next voltage point is received. This results in a stair-step output which can be smoothed or filtered if desired, as described below.
an ASK signal 4114illustrates the ASK signal 4112 , after filtering, on a compressed time scale.
FIG. 41Eillustrates the ASK signal 4114 as a filtered output signal
the output signaldoes not need to be filtered or smoothed to be within the scope of the invention. Instead, the output signal can be tailored for different applications.
the ASK signal 4114can be demodulated through any conventional amplitude demodulation technique When down-converting from FM to AM, the aliasing rate of the under-sampling signal is preferably controlled to optimize the demodulated baseband signal for amplitude output and/or polarity, as desired.
the aliasing rateis based on the second frequency and the resultant ASK signal is reversed relative to the ASK signal 4114 .
FIG. 41Eillustrates that the FSK carrier signal 816 was successfully down-converted to the ASK signal 4114 by retaining enough baseband information for sufficient reconstruction.
the under-sampling module 1606receives the FSK signal 816 (FIG. 41 A).
the under-sampling module 1606receives the under-sampling signal 4107 (FIG. 41 C).
the under-sampling module 1606under-samples the FSK signal 816 at the aliasing of the under-sampling signal 4107 to down-convert the FSK signal 816 to the ASK signal 4112 of FIG. 41D or the ASK signal 4114 in FIG. 41 E.
FIG. 13illustrates a generic aliasing system 1302 , including an aliasing module 1306 .
FIG. 16illustrates an under-sampling system 1602 , which includes an under-sampling module 1606 .
the under-sampling module 1606receives an under-sampling signal 1604 having an aliasing rate F AR .
the under-sampling signal 1604includes a train of pulses having negligible apertures that tend towards zero time in duration.
the pulsesrepeat at the aliasing rate F AR .
the under-sampling system 1602is an example implementation of the generic aliasing system 1303 .
the under-sampling system 1602outputs a down-converted signal 1308 A.
FIG. 26Aillustrates an exemplary sample and hold system 2602 , which is an exemplary implementation of the under-sampling system 1602 .
the sample and hold system 2602is described below.
FIG. 26Billustrates an exemplary inverted sample and hold system 2606 , which is an alternative example implementation of the under-sampling system 1602 .
the inverted sample and hold system 2606is described below.
FIG. 26Ais a block diagram of a the sample and hold system 2602 , which is an example embodiment of the under-sampling module 1606 in FIG. 16, which is an example embodiment of the generic aliasing module 1306 in FIG. 13 .
the sample and hold system 2602includes a sample and hold module 2604 , which receives the EM signal 1304 and the under-sampling signal 1604 .
the sample and hold module 2604under-samples the EM signal at the aliasing rate of the under-samnpling signal 1604 , as described in the sections above with respect to the flowcharts 1401 in FIG. 14A, 1407 in FIG. 14B, 1413 in FIG. 14C and 1419 in FIG. 14 D.
the under-sampling system 1602outputs a down-converted signal 1308 A.
FIG. 27illustrates an under-sampling system 2701 as a sample and hold system, which is an example implementation of the under-sampling system 2602 .
the under-sampling system 2701includes a switch module 2702 and a holding module 2706 .
the under-sampling system 2701is described below.
FIG. 24Aillustrates an under-sampling system 2401 as a break before make under-sampling system, which is an alternative implementation of the under-sampling system 2602 .
the break before make under-sampling system 2401is described below.
FIG. 27illustrates an exemplary embodiment of the sample and hold module 2604 from FIG. 26 A.
the sample and hold module 2604includes a switch module 2702 , and a holding module 2706 .
the switch module 2702 and the holding module 2706under-sample the EM signal 1304 to down-convert it in any of the manners shown in the operation flowcharts 1401 , 1407 , 1413 and 1419 .
the sample and hold module 2604can receive and under-sample any of the modulated carrier signal signals described above, including, but not limited to, the analog AM signal 516 , the digital AM signal 616 , the analog FM signal 716 , the digital FM signal 816 , the analog PM signal 916 , the digital PM signal 1016 , etc., and any combinations thereof.
the switch module 2702 and the holding module 2706down-convert the EM signal 1304 to an intermediate signal, to a demodulated baseband or to a different modulation scheme, depending upon the aliasing rate.
switch module 2702 and the holding module 2706are now described for down-converting the EM signal 1304 to an intermediate signal, with reference to the flowchart 1407 and the example timing diagrams in FIGS. 79A-F.
the switch module 2702receives the EM signal 1304 (FIG. 79 A). In step 1410 , the switch module 2702 receives the under-sampling signal 1604 (FIG. 79 C). In step 1412 , the switch module 2702 and the holding module 2706 cooperate to under-sample the EM signal 1304 and down-convert it to an intermediate signal. More specifically, during step 1412 , the switch module 2702 closes during each under-sampling pulse to couple the EM signal 1304 to the holding module 2706 . In an embodiment, the switch module 2702 closes on rising edges of the pulses. In an alternative embodiment, the switch module 2702 closes on falling edges of the pulses.
FIG. 79Billustrates the EM signal 1304 after under-sampling.
the holding module 2706substantially holds or maintains each under-sampled amplitude until a subsequent under-sample. (FIG. 79 D).
the holding module 2706outputs the under-sampled amplitudes as the down-converted signal 1308 A.
the holding module 2706can output the down-converted signal 1308 A as an unfiltered signal, such as a stair step signal (FIG. 79 E), as a filtered down-converted signal (FIG. 79F) or as a partially filtered down-converted signal.
FIG. 24Aillustrates a break-before-make under-sampling system 2401 , which is an alternative implementation of the under-sampling system 2602 .
the break-before-make under-sampling system 2401under-samples the EM signal 1304 to down-convert it in any of the manners shown in the operation flowcharts 1401 , 1407 , 1413 and 1419 .
the sample and hold module 2604can receive and under-sample any of the unmodulated or modulated carrier signal signals described above, including, but not limited to, the analog AM signal 516 , the digital AM signal 616 , the analog FM signal 716 , the digital FM signal 816 , the analog PM signal 916 , the digital PM signal 1016 , etc., and combinations thereof.
the break-before-make under-sampling system 2401down-converts the EM signal 1304 to an intermediate signal, to a demodulated baseband or to a different modulation scheme, depending upon the aliasing rate.
FIG. 24Aincludes a break-before-make switch 2402 .
the break-before-make switch 2402includes a normally open switch 2404 and a normally closed switch 2406 .
the normally open switch 2404is controlled by the under-sampling signal 1604 , as previously described.
the normally closed switch 2406is controlled by an isolation signal 2412 .
the isolation signal 2412is generated from the under-sampling signal 1604 .
the under-sampling signal 1604is generated from the isolation signal 2412 .
the isolation signal 2412is generated independently from the under-sampling signal 1604 .
the break-before-make module 2402substantially isolates a sample and hold input 2408 from a sample and hold output 2410 .
FIG. 24Billustrates an example timing diagram of the under-sampling signal 1604 that controls the normally open switch 2404 .
FIG. 24Cillustrates an example timing diagram of the isolation signal 2412 that controls the normally closed switch 2406 . Operation of the break-before-make module 2402 is described with reference to the example timing diagrams in FIGS. 24B and 24C.
the isolation signal 2412 in FIG. 24Copens the normally closed switch 2406 .
the under-sampling signal 1604 in FIG. 24Bbriefly closes the normally open switch 2404 . This couples the EM signal 1304 to the holding module 2416 .
the under-sampling signal 1604 in FIG. 24Bopens the normally open switch 2404 . This de-couples the EM signal 1304 from the holding module 2416 .
the isolation signal 2412 in FIG. 24Ccloses the normally closed switch 2406 . This couples the holding module 2416 to the output 2410 .
the break-before-make under-sampling system 2401includes a holding module 2416 , which can be similar to the holding module 2706 in FIG. 27 .
the break-before-make under-sampling system 2401down-converts the EM signal 1304 in a manner similar to that described with reference to the under-sampling system 2702 in FIG. 27 .
the switch module 2702 in FIG. 27 and the switch modules 2404 and 2406 in FIG. 24Acan be any type of switch device that preferably has a relatively low impedance when closed and a relatively high impedance when open.
the switch modules 2702 , 2404 and 2406can be implemented with normally open or normally closed switches.
the switch deviceneed not be an ideal switch device.
FIG. 28Billustrates the switch modules 2702 , 2404 and 2406 as, for example, a switch module 2810 .
the switch device 2810(e.g., switch modules 2702 , 2404 and 2406 ) can be implemented with any type of suitable switch device, including, but not limited to mechanical switch devices and electrical switch devices, optical switch devices, etc., and combinations thereof. Such devices include, but are not limited to transistor switch devices, diode switch devices, relay switch devices, optical switch devices, micro-machine switch devices, etc.
the switch module 2810can be implemented as a transistor, such as, for example, a field effect transistor (FET), a bi-polar transistor, or any other suitable circuit switching device.
a transistorsuch as, for example, a field effect transistor (FET), a bi-polar transistor, or any other suitable circuit switching device.
the switch module 2810is illustrated as a FET 2802 .
the FET 2802can be any type of FET, including, but not limited to, a MOSFET, a JFET, a GaAsFET, etc.
the FET 2802includes a gate 2804 , a source 2806 and a drain 2808 .
the gate 2804receives the under-sampling signal 1604 to control the switching action between the source 2806 and the drain 2808 .
the source 2806 and the drain 2808are interchangeable.
switch module 2810as a FET 2802 in FIG. 28A is for example purposes only. Any device having switching capabilities could be used to implement the switch module 2810 (e.g., switch modules 2702 , 2404 and 2406 ), as will be apparent to persons skilled in the relevant art(s) based on the discussion contained herein.
the switch module 2810is illustrated as a diode switch 2812 , which operates as a two lead device when the under-sampling signal 1604 is coupled to the output 2813 .
the switch module 2810is illustrated as a diode switch 2814 , which operates as a two lead device when the under-sampling signal 1604 is coupled to the output 2815 .
the holding modules 2706 and 2416preferably captures and holds the amplitude of the original, unaffected, EM signal 1304 within the short time frame of each negligible aperture under-sampling signal pulse.
holding modules 2706 and 2416are implemented as a reactive holding module 2901 in FIG. 29A, although the invention is not limited to this embodiment.
a reactive holding moduleis a holding module that employs one or more reactive electrical components to preferably quickly charge to the amplitude of the EM signal 1304 .
Reactive electrical componentsinclude, but are not limited to, capacitors and inductors.
the holding modules 2706 and 2416include one or more capacitive holding elements, illustrated in FIG. 29B as a capacitive holding module 2902 .
the capacitive holding module 2902is illustrated as one or more capacitors illustrated generally as capacitor(s) 2904 .
the preferred goal of the holding modules 2706 and 2416is to quickly charge to the amplitude of the EM signal 1304 .
the capacitive value of the capacitor 2904can tend towards zero Farads.
Example values for the capacitor 2904can range from tens of pico Farads to fractions of pico Farads.
a terminal 2906serves as an output of the sample and hold module 2604 .
the capacitive holding module 2902provides the under-samples at the terminal 2906 , where they can be measured as a voltage.
FIG. 29Fillustrates the capacitive holding module 2902 as including a series capacitor 2912 , which can be utilized in an inverted sample and hold system as described below.
the holding modules 2706 and 2416include one or more inductive holding elements, illustrated in FIG. 29D as an inductive holding module 2908 .
the holding modules 2706 and 2416include a combination of one or more capacitive holding elements and one or more inductive holding elements, illustrated in FIG. 29E as a capacitive/inductive holding module 2910 .
FIG. 29Gillustrates an integrated under-sampling system that can be implemented to down-convert the EM signal 1304 as illustrated in, and described with reference to, FIGS. 79A-F.
FIG. 30illustrates an under-sampling system 3001 , which is an example embodiment of the under-sampling system 1602 .
the under-sampling system 3001includes an optional under-sampling signal module 3002 that can perform any of a variety of functions or combinations of functions, including, but not limited to, generating the under-sampling signal 1604 .
the optional under-sampling signal module 3002includes an aperture generator, an example of which is illustrated in FIG. 29J as an aperture generator 2920 .
the aperture generator 2920generates negligible aperture pulses 2926 from an input signal 2924 .
the input signal 2924can be any type of periodic signal, including, but not limited to, a sinusoid, a square wave, a saw-tooth wave, etc. Systems for generating the input signal 2924 are described below.
the width or aperture of the pulses 2926is determined by delay through the branch 2922 of the aperture generator 2920 .
the tolerance requirements of the aperture generator 2920increase.
the components utilized in the example aperture generator 2920require greater reaction times, which are typically obtained with more expensive elements, such as gallium arsenide (GaAs), etc.
the example logic and implementation shown in the aperture generator 2920are provided for illustrative purposes only, and are not limiting. The actual logic employed can take many forms.
the example aperture generator 2920includes an optional inverter 2928 , which is shown for polarity consistency with other examples provided herein.
An example implementation of the aperture generator 2920is illustrated in FIG. 29 K.
FIGS. 29H and 29IAdditional examples of aperture generation logic is provided in FIGS. 29H and 29I.
FIG. 29Hillustrates a rising edge pulse generator 2940 , which generates pulses 2926 on rising edges of the input signal 2924 .
FIG. 29Iillustrates a falling edge pulse generator 2950 , which generates pulses 2926 on falling edges of the input signal 2924 .
the input signal 2924is generated externally of the under-sampling signal module 3002 , as illustrated in FIG. 30 .
the input signal 2924is generated internally by the under-sampling signal module 3002 .
the input signal 2924can be generated by an oscillator, as illustrated in FIG. 29L by an oscillator 2930 .
the oscillator 2930can be internal to the under-sampling signal module 3002 or external to the under-sampling signal module 3002 .
the oscillator 2930can be external to the under-sampling system 3001 .
the type of down-conversion performed by the under-sampling system 3001depends upon the aliasing rate of the under-sampling signal 1604 , which is determined by the frequency of the pulses 2926 .
the frequency of the pulses 2926is determined by the frequency of the input signal 2924 .
the EM signal 1304is directly down-converted to baseband (e.g. when the EM signal is an AM signal or a PM signal), or converted from FM to a non-FM signal.
the frequency of the input signal 2924is substantially equal to a harmonic or a sub-harmonic of a difference frequency
the EM signal 1304is down-converted to an intermediate signal.
the optional under-sampling signal module 3002can be implemented in hardware, software, firmware, or any combination thereof.
FIG. 26Billustrates an exemplary inverted sample and hold system 2606 , which is an alternative example implementation of the under-sampling system 1602 .
FIG. 42illustrates a inverted sample and hold system 4201 , which is an example implementation of the inverted sample and hold system 2606 in FIG. 26 B.
the sample and hold system 4201includes a sample and hold module 4202 , which includes a switch module 4204 and a holding module 4206 .
the switch module 4204can be implemented as described above with reference to FIGS. 28A-D.
the holding module 4206can be implemented as described above with reference to FIGS. 29A-F, for the holding modules 2706 and 2416 .
the holding module 4206includes one or more capacitors 4208 .
the capacitor(s) 4208are selected to pass higher frequency components of the EM signal 1304 through to a terminal 4210 , regardless of the state of the switch module 4204 .
the capacitor 4208stores charge from the EM signal 1304 during aliasing pulses of the under-sampling signal 1604 and the signal at the terminal 4210 is thereafter off-set by an amount related to the charge stored in the capacitor 4208 .
FIGS. 34A-FOperation of the inverted sample and hold system 4201 is illustrated in FIGS. 34A-F.
FIG. 34Aillustrates an example EM signal 1304 .
FIG. 34Billustrates the EM signal 1304 after under-sampling.
FIG. 34Cillustrates the under-sampling signal 1606 , which includes a train of aliasing pulses having negligible apertures.
FIG. 34Dillustrates an example down-onverted signal 1308 A.
FIG. 34Eillustrates the down-converted signal 1308 A on a compressed time scale. Since the holding module 4206 is series element, the higher frequencies (e.g., RF) of the EM signal 1304 can be seen on the down-converted signal. This can be filtered as illustrated in FIG. 34 F.
RFradio frequency
the inverted sample and hold system 4201can be used to down-convert any type of EM signal, including modulated carrier signals and unmodulated carrier signals, to IF signals and to demodulated baseband signals.
the optional under-sampling signal module 3002 in FIG. 30includes a pulse generator module that generates aliasing pulses at a multiple of the frequency of the oscillating source, such as twice the frequency of the oscillating source.
the input signal 2926may be any suitable oscillating source.
FIG. 31illustrates an example circuit 3102 that generates a doubler output signal 3104 (FIGS. 31 and 43B) that may be used as an under-sampling signal 1604 .
the example circuit 3102generates pulses on rising and falling edges of the input oscillating signal 3106 of FIG. 31 B.
Input oscillating signal 3106is one embodiment of optional input signal 2926 .
the circuit 3102can be implemented as a pulse generator and aliasing rate (F AR ) doubler, providing the under-sampling signal 1604 to under-sampling module 1606 in FIG. 30 .
F ARpulse generator and aliasing rate
the aliasing rateis twice the frequency of the input oscillating signal F OSC 3106 , as shown by EQ. (9) below.
the aperture width of the aliasing pulsesis determined by the delay through a first inverter 3108 of FIG. 31 . As the delay is increased, the aperture is increased. A second inverter 3112 is shown to maintain polarity consistency with examples described elsewhere. In an alternate embodiment inverter 3112 is omitted. Preferably, the pulses have negligible aperture widths that tend toward zero time.
the doubler output signal 3104may be further conditioned as appropriate to drive a switch module with negligible aperture pulses.
the circuit 3102may be implemented with integrated circuitry, discretely, with equivalent logic circuitry, or with any valid fabrication technology.
the inventioncan be implemented in a variety of differential configurations. Differential configurations are useful for reducing common mode noise. This can be very useful in receiver systems where common mode interference can be caused by intentional or unintentional radiators such as cellular phones, CB radios, electrical appliances etc. Differential configurations are also useful in reducing any common mode noise due to charge injection of the switch in the switch module or due to the design and layout of the system in which the invention is used. Any spurious signal that is induced in equal magnitude and equal phase in both input leads of the invention will be substantially reduced or eliminated. Some differential configurations, including some of the configurations below, are also useful for increasing the voltage and/or for increasing the power of the down-converted signal 1308 A.
differential under-sampling moduleWhile an example of a differential under-sampling module is shown below, the example is shown for the purpose of illustration, not limitation. Alternate embodiments (including equivalents, extensions, variations, deviations, etc.) of the embodiment described herein will be apparent to those skilled in the relevant art based on the teachings contained herein. The invention is intended and adapted to include such alternate embodiments.
FIG. 44Aillustrates an example differential system 4402 that can be included in the under-sampling module 1606 .
the differential system 4202includes an inverted under-sampling design similar to that described with reference to FIG. 42 .
the differential system 4402includes inputs 4404 and 4406 and outputs 4408 and 4410 .
the differential system 4402includes a first inverted sample and hold module 4412 , which includes a holding module 4414 and a switch module 4416 .
the differential system 4402also includes a second inverted sample and hold module 4418 , which includes a holding module 4420 and the switch module 4416 , which it shares in common with sample and hold module 4412 .
One or both of the inputs 4404 and 4406are coupled to an EM signal source.
the inputscan be coupled to an EM signal source, wherein the input voltages at the inputs 4404 and 4406 are substantially equal in amplitude but 180 degrees out of phase with one another.
one of the inputs 4404 and 4406can be coupled to ground.
the holding modules 4414 and 4420are in series and, provided they have similar capacitive values, they charge to equal amplitudes but opposite polarities.
the switch module 4416is open, the voltage at the output 4408 is relative to the input 4404 , and the voltage at the output 4410 is relative to the voltage at the input 4406 .
Portions of the voltages at the outputs 4408 and 4410include voltage resulting from charge stored in the holding modules 4414 and 4420 , respectively, when the switch module 4416 was closed.
the portions of the voltages at the outputs 4408 and 4410 resulting from the stored chargeare generally equal in amplitude to one another but 180 degrees out of phase.
Portions of the voltages at the outputs 4408 and 4410also include ripple voltage or noise resulting from the switching action of the switch module 4416 . But because the switch module is positioned between the two outputs, the noise introduced by the switch module appears at the outputs 4408 and 4410 as substantially equal and in-phase with one another. As a result, the ripple voltage can be substantially filtered out by inverting the voltage at on